Chemistry › Organic Chemistry

Chemical Thermodynamics and Molecular Structure

Works Count: 83471

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This cluster of papers focuses on the thermochemical properties of organic and organometallic compounds, including enthalpies of vaporization and sublimation, calorimetry techniques, standard molar enthalpies, and heat capacities. It also covers topics such as atomic weights and standard absolute entropy values.

Keywords

Enthalpies; Vaporization; Sublimation; Calorimetry; Thermodynamics; Organic Compounds; Atomic Weights; Standard Molar Enthalpies; Heat Capacities; Vapor Pressures

JANAF THERMOCHEMICAL TABLES

1989-12-01

D. R. Stull

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTJANAF THERMOCHEMICAL TABLESCite this: Anal. Chem. 1989, 61, 23, 1327APublication Date (Print):December 1, 1989Publication History Published online30 May 2012Published inissue 1 December 1989https://doi.org/10.1021/ac00198a726RIGHTS & PERMISSIONSArticle Views624Altmetric-Citations4LEARN ABOUT … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTJANAF THERMOCHEMICAL TABLESCite this: Anal. Chem. 1989, 61, 23, 1327APublication Date (Print):December 1, 1989Publication History Published online30 May 2012Published inissue 1 December 1989https://doi.org/10.1021/ac00198a726RIGHTS & PERMISSIONSArticle Views624Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (128 KB) Get e-Alerts Get e-Alerts

Thermochemical data of pure substances

1993-10-01

Ihsan Barin

Part 1 Basic principles: thermodynamic functions and relations - the basic concepts, the first law of thermodynamics, Joule-Thomson effect, the second law of thermodynamics, the third law of thermodynamics (Nernst … Part 1 Basic principles: thermodynamic functions and relations - the basic concepts, the first law of thermodynamics, Joule-Thomson effect, the second law of thermodynamics, the third law of thermodynamics (Nernst heat theorem), fundamental relations of thermodynamics, closed system with reactions, chemical potential, chemical equilibrium, mixtures, Gibbs phase rule, electrochemical reactions calculations of thermochemical functions - units and conventions, calculations of the thermochemical functions of pure substances, equilibrium calculations, exergy and entropy balances. Part 2 Compilation and presentation of thermochemical data: compilation of thermochemical data - basic thermochemical data, existing compilations, thermochemical tables. Part 3 Tables in the present work: preparation of the tables - general remarks, data sources, accuracy, units, standard states, reference phase for the elements at 298.15K and 1 bar construction of the tables - arrangement of substances, order of the phases in the tables contents and structure of the tables - formula, name and relative molar mass, tabulated functions, sequence of temperatures, phase transitions, the final temperature in the tables, references for the sources of data, abbreviations and symbols. Part 4 Examples of the use of the tables: examples of thermodynamic calculations - enthalpy changes, exergy and entropy balance calculations, equilibrium calculations, equilibrium in simplified systems with several phases and components, electrochemical energy conversion, high temperature fuel cell, the calculation of equilibria in multi-phases, multicomponent systems. Part 5 Information on the tables: fundamental constants and conversion factors - fundamental constants, conversion factors for energy units, conversions for entropies of gases, relative atomic masses of the elements based on A...=12 for 12C. Part 6 Symbols, abbreviations and references: symbols and abbreviations used in the tables reference phases of elements at 1 bar references for the data in the tables. Part 7 The tables: tables of thermochemical data of pure substances.

Selected Values of the Thermodynamic Properties of the Elements

1973-01-01

Ralph Hultgren , Pramod D. Desai , Donald T. Hawkins +2 more

Abstract : Contents: Methods of evaluation, atomic weights, fundamental constants, symbols and units, general references, and properties of the elements. Abstract : Contents: Methods of evaluation, atomic weights, fundamental constants, symbols and units, general references, and properties of the elements.

Density Functional Theory of Atoms and Molecules

1980-01-01

Robert G. Parr

Constants of diatomic molecules

1979-01-01

Klaus Huber , G. Herzberg

Spectra of diatomic molecules

1950-01-01

G. Herzberg , J. W. T. Spinks

Molecular spectra and molecular structure, iv, constants of diatomic molecules

1980-05-01

W.J. Orville-Thomas

Thermodynamic properties of minerals and related substances at 298.15 K and 1 bar (105 pascals) pressure and at higher temperatures

1978-01-01

Richard A. Robie , Bruce S. Hemingway

A report about values for the entropy, molar volume, and for the enthalpy and Gibbs energy of formation for the elements and minerals and substances at 298.15 K. A report about values for the entropy, molar volume, and for the enthalpy and Gibbs energy of formation for the elements and minerals and substances at 298.15 K.

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ON THE COLORIMETRIC DETERMINATION OF CREATININE BY THE JAFFE REACTION

1945-05-01

Roy W. Bonsnes , Hertha H. Taussky

Parst: A system of fortran routines for calculating molecular structure parameters from results of crystal structure analyses

1983-01-01

M. Nardelli

Approximate Self-Consistent Molecular Orbital Theory. I. Invariant Procedures

1965-11-15

John A. Pople , D. P. Santry , Gerald A. Segal

A general discussion of approximate methods for obtaining self-consistent molecular orbitals for all valence electrons of large molecules is presented. It is shown that the procedure of neglecting differential overlap … A general discussion of approximate methods for obtaining self-consistent molecular orbitals for all valence electrons of large molecules is presented. It is shown that the procedure of neglecting differential overlap in electron-interaction integrals (familiar in π-electron theory) without further adjustment may lead to results which are not invariant to simple transformations of the atomic orbital basis set such as rotation of axes or replacement of s, p orbitals by hybrids. The behavior of approximate methods in this context is examined in detail and two schemes are found which are invariant to transformations among atomic orbitals on a given atom. One of these (the simpler but more approximate) involves the complete neglect of differential overlap (CNDO) in all basis sets connected by such transformations. The other involves the neglect of diatomic differential overlap (NDDO) only, that is only products of orbitals on different atoms being neglected in the electron-repulsion integrals.

SGTE data for pure elements

1991-10-01

Alan Dinsdale

Density-functional thermochemistry. V. Systematic optimization of exchange-correlation functionals

1997-11-22

Axel D. Becke

A systematic procedure for refining gradient corrections in Kohn–Sham exchange-correlation functionals is presented. The procedure is based on least-squares fitting to accurate thermochemical data. In this first application of the … A systematic procedure for refining gradient corrections in Kohn–Sham exchange-correlation functionals is presented. The procedure is based on least-squares fitting to accurate thermochemical data. In this first application of the method, we use the G2 test set of Pople and co-workers to generate what we believe to be an optimum GGA/exact-exchange density-functional theory (i.e., generalized gradient approximation with mixing of exactly computed exchange).

Optimization of parameters for semiempirical methods V: Modification of NDDO approximations and application to 70 elements

2007-09-08

James J. P. Stewart

Several modifications that have been made to the NDDO core-core interaction term and to the method of parameter optimization are described. These changes have resulted in a more complete parameter … Several modifications that have been made to the NDDO core-core interaction term and to the method of parameter optimization are described. These changes have resulted in a more complete parameter optimization, called PM6, which has, in turn, allowed 70 elements to be parameterized. The average unsigned error (AUE) between calculated and reference heats of formation for 4,492 species was 8.0 kcal mol−1. For the subset of 1,373 compounds involving only the elements H, C, N, O, F, P, S, Cl, and Br, the PM6 AUE was 4.4 kcal mol−1. The equivalent AUE for other methods were: RM1: 5.0, B3LYP 6–31G*: 5.2, PM5: 5.7, PM3: 6.3, HF 6–31G*: 7.4, and AM1: 10.0 kcal mol−1. Several long-standing faults in AM1 and PM3 have been corrected and significant improvements have been made in the prediction of geometries.

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MOPAC: A semiempirical molecular orbital program

1990-03-01

James J. P. Stewart

Optimized intermolecular potential functions for liquid hydrocarbons

1984-10-01

William L. Jorgensen , Jeffry D. Madura , Carol J. Swenson

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptimized intermolecular potential functions for liquid hydrocarbonsWilliam L. Jorgensen, Jeffry D. Madura, and Carol J. SwensonCite this: J. Am. Chem. Soc. 1984, 106, 22, 6638–6646Publication Date (Print):October … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTOptimized intermolecular potential functions for liquid hydrocarbonsWilliam L. Jorgensen, Jeffry D. Madura, and Carol J. SwensonCite this: J. Am. Chem. Soc. 1984, 106, 22, 6638–6646Publication Date (Print):October 1, 1984Publication History Published online1 May 2002Published inissue 1 October 1984https://pubs.acs.org/doi/10.1021/ja00334a030https://doi.org/10.1021/ja00334a030research-articleACS PublicationsRequest reuse permissionsArticle Views7804Altmetric-Citations1972LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Optimization of parameters for semiempirical methods VI: more modifications to the NDDO approximations and re-optimization of parameters

2012-11-28

James J. P. Stewart

Modern semiempirical methods are of sufficient accuracy when used in the modeling of molecules of the same type as used as reference data in the parameterization. Outside that subset, however, … Modern semiempirical methods are of sufficient accuracy when used in the modeling of molecules of the same type as used as reference data in the parameterization. Outside that subset, however, there is an abundance of evidence that these methods are of very limited utility. In an attempt to expand the range of applicability, a new method called PM7 has been developed. PM7 was parameterized using experimental and high-level ab initio reference data, augmented by a new type of reference data intended to better define the structure of parameter space. The resulting method was tested by modeling crystal structures and heats of formation of solids. Two changes were made to the set of approximations: a modification was made to improve the description of noncovalent interactions, and two minor errors in the NDDO formalism were rectified. Average unsigned errors (AUEs) in geometry and ΔH f for PM7 were reduced relative to PM6; for simple gas-phase organic systems, the AUE in bond lengths decreased by about 5 % and the AUE in ΔH f decreased by about 10 %; for organic solids, the AUE in ΔH f dropped by 60 % and the reduction was 33.3 % for geometries. A two-step process (PM7-TS) for calculating the heights of activation barriers has been developed. Using PM7-TS, the AUE in the barrier heights for simple organic reactions was decreased from values of 12.6 kcal/mol-1 in PM6 and 10.8 kcal/mol-1 in PM7 to 3.8 kcal/mol-1. The origins of the errors in NDDO methods have been examined, and were found to be attributable to inadequate and inaccurate reference data. This conclusion provides insight into how these methods can be improved.

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Evaluated Kinetic Data for Combustion Modelling

1992-05-01

D. L. Baulch , Carlos J. Cobos , R. A. Cox +7 more

This compilation contains critically evaluated kinetic data on elementary homogeneous gas phase for use in modelling processes. Data sheets are presented for some 196 Each data sheet sets out relevant … This compilation contains critically evaluated kinetic data on elementary homogeneous gas phase for use in modelling processes. Data sheets are presented for some 196 Each data sheet sets out relevant data, rate coefficient measurements, an assessment of the reliability of the data, references, and recommended rate parameters. Tables summarizing the preferred rate data are also given. The considered are limited largely to those involved in the of and ethane in air but a few relevant to the chemistry of exhaust gases and to the of aromatic compounds are also included.

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Gaussian-Type Functions for Polyatomic Systems. II

1969-02-01

Sigeru Huzinaga , Yoshiko Sakai

The use of a linear combination of Gaussian-type orbitals (CGTO), instead of an individual Gaussian-type orbital (GTO), as a unit of basis functions for large-scale molecular calculations, is discussed. A … The use of a linear combination of Gaussian-type orbitals (CGTO), instead of an individual Gaussian-type orbital (GTO), as a unit of basis functions for large-scale molecular calculations, is discussed. A systematic construction of the CGTO basis functions is attempted and the results for the atoms from Li through Ar are reported.

The work function of the elements and its periodicity

1977-11-01

Herbert B. Michaelson

A new compilation, based on a literature search for the period 1969–1976, is made of experimental data on the work function. For these 44 elements, preferred values are selected on … A new compilation, based on a literature search for the period 1969–1976, is made of experimental data on the work function. For these 44 elements, preferred values are selected on the basis of valid experimental conditions. Older values, which are widely accepted, are given for 19 other elements on which there is no recent literature, and are so identified. In the data for the 63 elements, trends that occur simultaneously in both the columns and the rows of the periodic table are shown to be useful in predicting correct values and also for identifying questionable data. Several illustrative examples are given, including verifications of predictions published in 1950.

Chemical Kinetic Data Base for Combustion Chemistry. Part I. Methane and Related Compounds

1986-07-01

Wing Tsang , R. F. Hampson

This document contains evaluated data on the kinetics and thermodynamic properties of species that are of importance in methane pyrolysis and combustion. Specifically, the substances considered include H, H2, O, … This document contains evaluated data on the kinetics and thermodynamic properties of species that are of importance in methane pyrolysis and combustion. Specifically, the substances considered include H, H2, O, O2, OH, HO2, H2O2, H2O, CH4, C2H6, HCHO, CO2, CO, HCO, CH3, C2H5, C2H4, C2H3, C2H2, C2H, CH3CO, CH3O2, CH3O, singlet CH2, and triplet CH2. All possible reactions are considered. In arriving at recommended values, first preference is given to experimental measurements. Where data do not exist, a best possible estimate is given. In making extrapolations, extensive use is made RRKM calculations for the pressure dependence of unimolecular processes and the BEBO method for hydrogen transfer reactions. In the total absence of data, recourse is made to the principle of detailed balancing, thermokinetic estimates, or comparisons with analogous reactions. The temperature range covered is 300–2500 K and the density range 1×1016–1×1021 molecules/cm3. This data base forms a subset of the chemical kinetic data base for all combustion chemistry processes. Additions and revisions will be issued periodically.

ESTIMATION OF PURE-COMPONENT PROPERTIES FROM GROUP-CONTRIBUTIONS

1987-07-01

Kevin G. Joback , Robert C. Reid

Abstract Simple group-contribution methods are proposed to estimate eleven important physical properties of pure materials. A common set of structural groups was employed. High accuracy is not claimed, but the … Abstract Simple group-contribution methods are proposed to estimate eleven important physical properties of pure materials. A common set of structural groups was employed. High accuracy is not claimed, but the proposed methods are often as accurate as or more accurate than techniques in common use today.

Density-functional thermochemistry. IV. A new dynamical correlation functional and implications for exact-exchange mixing

1996-01-15

Axel D. Becke

A new dynamical correlation functional is constructed subject to a small number of simple, yet key, requirements not all satisfied by existing functionals in the literature. The new functional gives … A new dynamical correlation functional is constructed subject to a small number of simple, yet key, requirements not all satisfied by existing functionals in the literature. The new functional gives good atomic correlation energies, and, in conjunction with previous gradient-corrected exchange functionals and exact-exchange mixing, excellent thermochemistry in the G2 benchmarks of Pople and co-workers.

Self-Consistent Molecular-Orbital Methods. IX. An Extended Gaussian-Type Basis for Molecular-Orbital Studies of Organic Molecules

1971-01-15

R. Ditchfield , Warren J. Hehre , John A. Pople

An extended basis set of atomic functions expressed as fixed linear combinations of Gaussian functions is presented for hydrogen and the first-row atoms carbon to fluorine. In this set, described … An extended basis set of atomic functions expressed as fixed linear combinations of Gaussian functions is presented for hydrogen and the first-row atoms carbon to fluorine. In this set, described as 4–31 G, each inner shell is represented by a single basis function taken as a sum of four Gaussians and each valence orbital is split into inner and outer parts described by three and one Gaussian function, respectively. The expansion coefficients and Gaussian exponents are determined by minimizing the total calculated energy of the atomic ground state. This basis set is then used in single-determinant molecular-orbital studies of a group of small polyatomic molecules. Optimization of valence-shell scaling factors shows that considerable rescaling of atomic functions occurs in molecules, the largest effects being observed for hydrogen and carbon. However, the range of optimum scale factors for each atom is small enough to allow the selection of a standard molecular set. The use of this standard basis gives theoretical equilibrium geometries in reasonable agreement with experiment.

Molecular Spectra and Molecular Structure. I. Spectra of Diatomic Molecules

1951-09-01

G. Herzberg , S. Mrozowski

First Page First Page

Assessment of Gaussian-2 and density functional theories for the computation of enthalpies of formation

1997-01-15

Larry A. Curtiss , Krishnan Raghavachari , Paul C. Redfern +1 more

A set of 148 molecules having well-established enthalpies of formation at 298 K is presented. This set, referred to as the G2 neutral test set, includes the 55 molecules whose … A set of 148 molecules having well-established enthalpies of formation at 298 K is presented. This set, referred to as the G2 neutral test set, includes the 55 molecules whose atomization energies were used to test Gaussian-2 (G2) theory [J. Chem. Phys. 94, 7221 (1991)] and 93 new molecules. The G2 test set includes 29 radicals, 35 nonhydrogen systems, 22 hydrocarbons, 47 substituted hydrocarbons, and 15 inorganic hydrides. It is hoped that this new test set will provide a means for assessing and improving new theoretical models. From an assessment of G2 and density functional theories (DFT) on this test set it is found that G2 theory is the most reliable method both in terms of average absolute deviation (1.58 kcal/mol) and maximum deviation (8.2 kcal/mol). The largest deviations between experiment and G2 theory occur for molecules having multiple halogens. Inclusion of spin–orbit effects reduces the average absolute deviation to 1.47 kcal/mol and significantly improves the results for the chlorine substituted molecules, but little overall improvement is seen for the fluorine substituted molecules. Of the two modified versions of G2 theory examined in this study, G2(MP2,SVP) theory (average absolute deviation=1.93 kcal/mol) performs better than G2(MP2) theory (2.04 kcal/mol). The G2(MP2,SVP) theory is found to perform very well for hydrocarbons, radicals, and inorganic hydrides. Of the seven DFT methods investigated, the B3LYP method has the smallest average absolute deviation (3.11 kcal/mol). It also has a significantly larger distribution of error than the G2 methods with a maximum deviation of 20.1 kcal/mol.

Definition of the halogen bond (IUPAC Recommendations 2013)

2013-07-10

Gautam R. Desiraju , P Shing Ho , Lars Kloo +6 more

This recommendation proposes a definition for the term “halogen bond”, which designates a specific subset of the inter- and intramolecular interactions involving a halogen atom in a molecular entity. This recommendation proposes a definition for the term “halogen bond”, which designates a specific subset of the inter- and intramolecular interactions involving a halogen atom in a molecular entity.

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Theoretical Chemistry of Gold

2004-08-25

Pekka Pyykkö

Gold is an element whose unique properties are strongly influenced by relativistic effects. A large body of appropriate calculations now exist and their main conclusions are summarized. The theoretical interpretation … Gold is an element whose unique properties are strongly influenced by relativistic effects. A large body of appropriate calculations now exist and their main conclusions are summarized. The theoretical interpretation of the aurophilic attraction is discussed in detail.

Bond Dissociation Energies of Organic Molecules

2003-01-28

Stephen J. Blanksby , G. Barney Ellison

In this Account we have compiled a list of reliable bond energies that are based on a set of critically evaluated experiments. A brief description of the three most important … In this Account we have compiled a list of reliable bond energies that are based on a set of critically evaluated experiments. A brief description of the three most important experimental techniques for measuring bond energies is provided. We demonstrate how these experimental data can be applied to yield the heats of formation of organic radicals and the bond enthalpies of more than 100 representative organic molecules.

Electronegativity values from thermochemical data

1961-06-01

A. L. Allred

Gas‐chromatographische Charakterisierung organischer Verbindungen. Teil 1: Retentionsindices aliphatischer Halogenide, Alkohole, Aldehyde und Ketone

1958-01-01

Ervin sz. Kováts

Abstract For the characterization of organic substances in gas chromatography a number termed « retention index » is proposed. A simple relation exists between the retention index of a compound … Abstract For the characterization of organic substances in gas chromatography a number termed « retention index » is proposed. A simple relation exists between the retention index of a compound on a non‐polar stationary phase and its boiling point.

The thermodynamic properties of isotopic substances

1947-01-01

Harold C. Urey

H. C. Urey, J. Chem. Soc., 1947, 562 DOI: 10.1039/JR9470000562 H. C. Urey, J. Chem. Soc., 1947, 562 DOI: 10.1039/JR9470000562

Characterization of electronic transitions in complex molecules

1950-01-01

Michael Kasha

M. Kasha, Discuss. Faraday Soc., 1950, 9, 14 DOI: 10.1039/DF9500900014 M. Kasha, Discuss. Faraday Soc., 1950, 9, 14 DOI: 10.1039/DF9500900014

Tables of bond lengths determined by X-ray and neutron diffraction. Part 1. Bond lengths in organic compounds

1987-01-01

Frank H. Allen , Olga Kennard , David J. Watson +3 more

The average lengths of bonds involving the elements H, B, C, N, O, F, Si, P, S, Cl, As, Se, Br, Te, and l in organic compounds are reported. The average lengths of bonds involving the elements H, B, C, N, O, F, Si, P, S, Cl, As, Se, Br, Te, and l in organic compounds are reported.

Thermochemical properties of inorganic substances

1977-01-01

Ihsan Barin , Ottmar Knacke , O. Kubaschewski

JANAF thermochemical tables

1972-05-01

Frederick D. Rossini

Structural Determination of Paraffin Boiling Points

1947-01-01

Harry Wiener

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural Determination of Paraffin Boiling PointsHarry WienerCite this: J. Am. Chem. Soc. 1947, 69, 1, 17–20Publication Date (Print):January 1, 1947Publication History Published online1 May 2002Published inissue 1 … ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStructural Determination of Paraffin Boiling PointsHarry WienerCite this: J. Am. Chem. Soc. 1947, 69, 1, 17–20Publication Date (Print):January 1, 1947Publication History Published online1 May 2002Published inissue 1 January 1947https://pubs.acs.org/doi/10.1021/ja01193a005https://doi.org/10.1021/ja01193a005research-articleACS PublicationsRequest reuse permissionsArticle Views3127Altmetric-Citations2878LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InRedditEmail Other access optionsGet e-Alertsclose Get e-Alerts

Density-functional theory of atoms and molecules

1989-01-01

James D. Patterson

Thermochemical properties of inorganic substances

1974-07-01

H. A. Skinner

Infrared spectra of inorganic and coordination compounds

1964-03-01

M. G. Mellon

Handbook of Chemometrics and Qualimetrics: Part A

1998-01-01

The Infrared Spectra of Complex Molecules

1980-01-01

L. J. Bellamy

Critical Stability Constants

1975-01-01

Robert M. Smith , Arthur E. Martell

Thermodynamic Properties of Individual Substances

1994-01-01

L. V. Gurvich , I.V. Veyts , C.B. Alcock

The third volume of this work deals with the properties of ten elements (boron, aluminum, gallium, indium, thallium, beryllium, magnesium, calcium, strontium, and barium) and their compounds with oxygen, hydrogen, … The third volume of this work deals with the properties of ten elements (boron, aluminum, gallium, indium, thallium, beryllium, magnesium, calcium, strontium, and barium) and their compounds with oxygen, hydrogen, halogens, sulphur, and some others. The second part of this volume contains 343 tables of thermodynamic properties including 93 substances in the condensed state and 273 substances in the gaseous state. For about 80 substances the tables of thermodynamic properties are published for the first time in the literature. In the course of preparation of this volume the authors had the opportunity to discuss the evaluation of different data with many Soviet and Western scientists. The evaluation of key thermochemical values for this volume coincided in time with the work of the CODATA-ICSU Task Group on Key Values for Thermodynamics, in which several authors of this book took part. Discussions with other members of the task group (Drs. W. Evans, D. D. Wagman, and J. Drowart) and also with Drs. I. L. Khodakovsky (Geokhi AN USSR), M. Chase (JANAF Group), and D. Hildenbrand (SRI) were extremely fruitful. The editors express sincere appreciation to them and to many other scientists for useful discussions and for providing results of their studies before publication. 716 pages, <big>©</big> 1994

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The thermochemical properties of 2- and 3-Thiophenemethanol: Eluding incomplete combustion issues through combining experimental and computational methodologies

2025-06-24

Fernando Ramos , David Ochoa-Resendiz , E. Adriana Camarillo +3 more | Thermochimica Acta

Examples and causes of peak-free zones in electron ionization mass spectra of linear compounds

2025-06-24

Nikolay Kagramanov | FLUORINE NOTES

Investigation of structural, electronic and toxicity profiles of pyrene, benzo[e]pyrene, and their ozonolysis products by using computational methods

2025-06-24

Dhyani Vadgama , Harshil Shah , Satyam Shinde +1 more | Journal of Molecular Modeling

Coalescent theory of the ψ directionality index

2025-06-24

Egor Lappo , Noah A. Rosenberg

Abstract The ψ directionality index was introduced by Peter & Slatkin ( Evolution 67: 3274-3289, 2013) to infer the direction of range expansions from single-nucleotide polymorphism variation. Computed from the … Abstract The ψ directionality index was introduced by Peter & Slatkin ( Evolution 67: 3274-3289, 2013) to infer the direction of range expansions from single-nucleotide polymorphism variation. Computed from the joint site frequency spectrum for two populations, ψ uses shared genetic variants to measure the difference in the amount of genetic drift experienced by the populations, associating excess drift with greater distance from the origin of the range expansion. Although ψ has been successfully applied in natural populations, its statistical properties have not been well understood. In this paper, we define Ψ as a random variable originating from a coalescent process in a two-population demography. For samples consisting of a pair of diploid genomes, one from each of two populations, we derive expressions for moments 𝔼 [Ψ k ] for standard parameterizations of bottlenecks during a founder event. For the expectation 𝔼[Ψ], we identify parameter combinations that represent distinct demographic scenarios yet yield the same value of 𝔼[Ψ]. We also show that the variance 𝕍[Ψ] increases with the time since the bottleneck, bottleneck severity, and size of the ancestral population. For a sample containing many SNPs, the central limit theorem allows us to approximate the distribution of the observed value of the ψ index conditional on the demographic history. Finally, we analyze the values of 𝔼[Ψ] computed from existing demographic models of Drosophila melanogaster and compare them with empirically computed ψ . Our work builds the foundation for theoretical treatments of the ψ index and can help in evaluating its behavior in empirical applications. Summary The statistic known as the “directionality index” examines variants shared between two populations with a goal of identifying which population has experienced a greater amount of genetic drift. This study develops theoretical predictions for the directionality index in coalescent models of pairs of populations descended from a common ancestral population. It determines the influence of bottlenecks, population growth, and population sizes on the directionality index. In Drosophila melanogaster , patterns in genomic data accord with the direction of the model predictions, with ψ suggesting a higher level of drift in European than in African populations.

Crystallisation thermodynamics of 3,4-bis(3-nitrofurazan-4-yl)furoxan (DNTF) in n-PrOH + water binary mixed solvents

2025-06-23

Li Xiao , Liang Qin , Debin Yang +3 more | Physics and Chemistry of Liquids

Evaluation of thermochemical characteristics of salts with pentazenium cation

2025-06-23

Dmitry V. Khakimov , Alexey A. Voronin | Journal of Molecular Modeling

Measurements and Modeling of Vapor–Liquid Equilibrium for Ternary Mixtures of R290+R1234ze(E)+CO2

2025-06-22

Yingqiang Qi , Xiaolei Xu , Jinwei Dong +2 more | Fluid Phase Equilibria

Sulfoxide bond dissociation enthalpies predicted by DFT paired with Pople, Dunning, and Karlsruhe basis sets

2025-06-20

Sydney S. Lahm , Ryan D. McCulla | Journal of Sulfur Chemistry

Formation of hydrogen bonding network of ethylurea-ammonium sulfamate complexes

2025-06-20

Bekzod Khudaykulov , Utkirjon Holikulov , Аleksandr S. Kazachenko +3 more | Journal of Computational Biophysics and Chemistry

Coulometric titration of sulfanilamide as a standard for diazotization titration and nitrite determination

2025-06-19

Toshiaki Asakai | Analytical and Bioanalytical Chemistry

Some isomers and tautomers of thiobarbital – A DFT treatment

2025-06-19

Lemi Türker | Earthline Journal of Chemical Sciences

Thiobarbital is characterized with its sedative and hypnotic properties; however it exhibits an antithyroid effect. Moreover it has a narrow range of therapeutic and toxic dose. In the present study, … Thiobarbital is characterized with its sedative and hypnotic properties; however it exhibits an antithyroid effect. Moreover it has a narrow range of therapeutic and toxic dose. In the present study, firstly thiobarbital and one of its structural isomer, constructed by mutual sulphur/oxygen replacements have been investigated thoroughly within the restrictions of density functional theory at the level of B3LYP/6-311++G(d,p). Secondly, its 1,3-proton tautomers have been considered at the same level of calculation. The collected data revealed that all the structures considered have exothermic heat of formation and favorable Gibbs free energy of formation values. They are thermally favored and electronically stable at the standard states. Various structural and quantum chemical data have been collected and discussed, including IR and UV-VIS spectra.

Heat Capacities of Aqueous Solutions of Nitric Acid to High Concentrations and Elevated Temperatures

2025-06-17

Xiong Xiao , L. Hnědkovský , Tuomas Vielma +1 more | Journal of Chemical & Engineering Data

Thermophysical Properties of Propaline + 1-Alcohols: An Experimental and Molecular Insight

2025-06-13

Guadalupe Pérez-Durán , Noor Alomari , Mariana Ramos-Estrada +2 more | International Journal of Thermophysics

Correction to: Guidance for measuring and evaluating biomagnification factors and trophic magnification factors of difficult substances: application to decabromodiphenylethane

2025-06-06

| Integrated Environmental Assessment and Management

26th International conference on chemical thermodynamics

2025-06-05

Intermolecular Interactions in Direct Air Capture Materials: Insights from Charge Density Analysis

2025-06-05

Sylwia Pawlȩdzio , Jeffrey D. Einkauf , Radu Custelcean +1 more | Journal of the American Chemical Society

Direct air capture (DAC) materials enable the removal of CO2 from the atmosphere, but improving their efficiency requires a detailed understanding of the intermolecular interactions that govern CO2 sorption and … Direct air capture (DAC) materials enable the removal of CO2 from the atmosphere, but improving their efficiency requires a detailed understanding of the intermolecular interactions that govern CO2 sorption and release. Here, we present an experimental electron density study of methylglyoxal-bis(iminoguanidine) (MGBIG), a promising DAC material, using high-resolution X-ray and neutron diffraction data combined with quantum crystallographic analysis. This approach bridges theoretical and experimental data by quantifying electron density distributions and revealing how hydrogen bonds stabilize CO2-derived carbonate phases and may influence the desorption behavior. We identify distinct hydrogen-bonding environments in two crystalline carbonate phases: P1, a transient kinetic product, and P3, a thermodynamically stable phase. Multipolar refinement and electrostatic potential and multipole moment calculations precisely map electron density distributions, revealing key hydrogen bonds involved in CO2 capture. Topological analysis of electron density highlights a cooperative hydrogen-bonding network in the thermodynamically favored P3 phase, where enhanced electron density delocalization and water-mediated interactions contribute to a more stable lattice. Energetic analyses confirm that stronger hydrogen bonding networks enhance the stability of P3 with a binding energy of -607.0 kJ/mol and greater lattice stability (-847.3 kJ/mol) compared to P1 (-302.5 and -571.0 kJ/mol, respectively). Electrostatic potential maps further illustrate polarization patterns that may influence the stability of the binding of CO2 and release conditions. These findings establish a direct experimental framework for linking electron density distributions to intermolecular interactions in DAC materials, providing a rational design strategy for optimizing sorbents with improved CO2 capture efficiency and reduced energy demands.

The simpler the better? Enthalpies of formation and entropies of short-chain chlorinated paraffines by ab initio, DFT, group additivity and semiempirical approximations

2025-06-04

Artem V Chaikin , Timofey P. Rozov , Alexander S. Ryzhako +3 more | Journal of Molecular Graphics and Modelling

MONITORING THE QUALITY OF LIQUID FUELS USING SPECTROSCOPY METHODS – SELECTION OF A LIGHT SOURCE

2025-06-01

Bożena Szczucka-Lasota , Tomasz Węgrzyn , Feng Chen +1 more | Scientific Journal of Silesian University of Technology Series Transport

The aim of the article is to develop a new measurement station for assessing the quality of liquid fuels using light spectroscopy methods. Tests were carried out using various light … The aim of the article is to develop a new measurement station for assessing the quality of liquid fuels using light spectroscopy methods. Tests were carried out using various light sources, transmittance and absorbance were determined, and sources for liquid fuel tests were selected. Fuel samples were prepared. At the developed stand, it was checked whether the developed measurement method is suitable for determining the quality of liquid fuel. The novelty of the article is to show that spectroscopy methods using appropriate light sources are a prospective solution for determining the quality of liquid fuels during continuous monitoring. The research was performed in laboratory conditions. The technology requires development and adaptation to real conditions; the research conducted is qualitative and not quantitative.

Thermal, Microstructural, and Phase Equilibria Investigations of an Organic Counterpart of a Nonmetal-Nonmetal Monotectic Alloy: 2-Cyanoacetamide-4-bromonitrobenzene System

2025-06-01

Balaji Babu , N. Hussain Basha , M. Sreenivasulu | Russian Journal of Physical Chemistry A

Liquid-liquid equilibria of systems containing 2-methoxyphenol or 2-ethoxyphenol and n-alkanes

2025-06-01

Cristina Alonso‐Tristán , João Victor Alves-Laurentino , Fatemeh Pazoki +3 more | Journal of Molecular Liquids

Correction of Thermal Inertia on Scanning Calorimetry

2025-06-01

Jürgen E. K. Schawe | Thermochimica Acta

Accurate gas-phase thermochemistry of commercially utilized brominated flame retardants

2025-06-01

Timofey P. Rozov , Artem V. Chaikin , Andrey D. Moshchenkov +3 more | Chemical Physics Letters

Experimental Thermochemistry Through the Years with Application to Chalcogenides

2025-05-30

Alexandra Navrotsky , Manuel Scharrer | Annual Review of Earth and Planetary Sciences

Investigation of Intermolecular Interactions of 2-Acetoxybenzoic Acid with Hirshfeld Surfaces

2025-05-30

Hanifi Kebiroglu , Mücahit Yılmaz | Bilecik Şeyh Edebali Üniversitesi Fen Bilimleri Dergisi

In this study, the crystal structure and intermolecular interactions of acetoxybenzoic acid were analyzed. Through crystal structure analysis, the arrangement of carbon (C), oxygen (O), and hydrogen (H) atoms, along … In this study, the crystal structure and intermolecular interactions of acetoxybenzoic acid were analyzed. Through crystal structure analysis, the arrangement of carbon (C), oxygen (O), and hydrogen (H) atoms, along with their chemical bonds, was determined. It was identified that oxygen atoms impart polar character to the molecule and play a significant role in intermolecular interactions, such as hydrogen bonding. Hirshfeld surface analysis, performed using CrystalExplorer software, focused on the interactions of the molecule with solvent molecules. This analysis provided a more comprehensive understanding of molecular interactions and structure. Additionally, properties such as electron density, curvature, and surface shape indices were mapped. The structural and electronic properties of acetoxybenzoic acid were visualized, offering a deeper understanding of its chemical and physical properties. XRD analysis revealed the crystallinity of the molecule and provided detailed insights into the crystal structure through the position of the peaks. This study illuminated the molecular structure and interaction properties of acetoxybenzoic acid, contributing to predictions of reactivity at the molecular level.

Theoretical Study of Molar Entropy and Gibbs Free Energy for HCl and DCl

2025-05-30

Jame Yao , Changlong Chen , Qunchao Fan +5 more | Physica Scripta

Abstract Molecular molar entropy and Gibbs free energy are pivotal for understanding the thermodynamic and kinetic properties of molecular systems, facilitating the optimization of chemical reactions and phase transitions. In … Abstract Molecular molar entropy and Gibbs free energy are pivotal for understanding the thermodynamic and kinetic properties of molecular systems, facilitating the optimization of chemical reactions and phase transitions. In this work, we integrated experimental spectral constants (De, re, ωe, ωeχe, Be, αe) and Rydberg-Klein-Rees (RKR) data, and constructed the potential energy curves (PECs) for the ground electronic states of HCl and DCl molecules using the variationally improved Hulburt-Hirschfelder (VIHH) potential model. The complete set of rovibrational energy levels for the ground electronic states of HCl and DCl is obtained by solving the one-dimensional Schrödinger equation. Finally, the molar entropy and the reduced Gibbs free energy of these two molecules in the temperature range of 100 to 6000K are calculated within the framework of quantum statistical theory. Our results demonstrate that the PECs and vibrational energy levels derived from the VIHH model align closely with experimental values, and the calculated thermodynamic properties are consistent with data from the National Institute of Standards and Technology.&#xD;

Deciphering Atomic Polarizability: The Absolute Radii and Orbital Contributions Visited

2025-05-29

Richa Khatiwada , Pengfei Li | The Journal of Physical Chemistry A

Polarizability is a fundamental property in molecular sciences. It depends on the atom and molecule size and characterizes the ease of deforming the electron cloud by an electric field. Previous … Polarizability is a fundamental property in molecular sciences. It depends on the atom and molecule size and characterizes the ease of deforming the electron cloud by an electric field. Previous studies suggested that the electronic distribution of the outermost orbital can be used to determine the ground-state properties of the atom like hardness, polarizability, and electronegativity. Additionally, the "absolute radius"─the most probable radius of the outermost orbital─has been used to derive atomic properties. In our study, we present a new set of absolute radii for various atoms and ions across the periodic table, obtained based on high-level quantum mechanical calculations. These radii exhibit greater accuracy compared to those previously derived using Slater shielding constants and could offer enhanced utility for diverse scientific applications. We also calculated atomic polarizabilities for a range of atoms and ions using three different approaches. One method assumes a spherical electron distribution based on the absolute radii, while the other two rely on the radial distribution function(s) of the outermost orbital(s). Comparisons with reference polarizabilities obtained from density functional theory (DFT) indicate that while these strategies provide qualitative insights, they do not yield quantitative agreement. To better understand the factors influencing atomic polarizability, we evaluated the contributions of different orbitals. Interestingly, our results reveal that inner orbitals contribute significantly to the atomic polarizability, which are comparable to the outermost orbital. This finding challenges the conventional view of polarizability as solely a volume-dependent property linked to the valence orbital. Moreover, our analysis of three molecules─CO2, CH4, and SF6─indicates that molecular polarizability is primarily governed by the outermost orbitals, likely because chemical bonds constrain the electron clouds of the inner orbitals, a limitation absent in isolated atoms. These findings imply that polarizability is best understood as a property influenced by both atomic volume and the energetic contributions of various orbitals.