Properties of atoms in molecules: Dipole moments and transferability of properties

1987 ◽  
Vol 87 (2) ◽  
pp. 1142-1152 ◽  
Author(s):  
R. F. W. Bader ◽  
A. Larouche ◽  
C. Gatti ◽  
M. T. Carroll ◽  
P. J. MacDougall ◽  
...  
Keyword(s):  
Dipole Moments ◽  
Atoms In Molecules

Variability of shapes and properties of atoms in molecules: a case study of the carbonyl oxygen

1996 ◽  
Vol 74 (6) ◽  
pp. 1263-1270 ◽  
Author(s):  
Boris B. Stefanov ◽  
Jerzy Cioslowski
Keyword(s):  
Electronic Properties ◽  
Dipole Moments ◽  
Visual Assessment ◽  
Carbonyl Oxygen ◽  
Atoms In Molecules ◽  
Large Molecules ◽  
Neighbor Effects ◽  
Theoretical Considerations ◽  
Oxygen Atoms

A comparative study of carbonyl oxygen atoms in diverse molecular environments is presented. The variability of shapes of oxygen atoms is quantified with a newly developed similarity measure that confirms the qualitative conclusions of visual assessment. Electronic properties of these atoms, such as charges, energies, and dipole moments, are computed and their possible correlations with the atomic shapes are studied. Factors that affect atomic shapes are investigated and found to be distinct from those influencing electronic properties of atoms in molecules. The kinetic energies of the atoms under study correlate poorly with the atomic charges. The second-neighbor effects on the atomic energies and charges are approximately additive. Both the theoretical considerations and the numerical results definitively rule out the possibility of the shapes of atomic basins unambiguously determining the properties of atoms in molecules. The consequences of this observation for the recently contemplated approaches to the prediction of electronic properties of large molecules are discussed. Key words: atoms in molecules, properties of —; similarity of —; transferability of —.

Atoms-in-molecules calculation of dipole moments of the lowest Σ and Π states of LiH

1985 ◽  
Vol 115 (6) ◽  
pp. 549-553 ◽  
Author(s):  
J. Vojtík ◽  
V. Říha ◽  
J. Šavrda
Keyword(s):  
Dipole Moments ◽  
Atoms In Molecules

Substituent effects on basicity in Group 15 compounds: an analysis based on proton affinities, charge distributions, and dipole polarizabilities

1997 ◽  
Vol 75 (1) ◽  
pp. 60-67 ◽  
Author(s):  
S.T. Howard ◽  
J.P. Foreman ◽  
P.G. Edwards
Keyword(s):  
Electric Field ◽  
Charge Distribution ◽  
Proton Affinity ◽  
Dipole Moments ◽  
Substituent Effects ◽  
Atoms In Molecules ◽  
Proton Affinities ◽  
Electric Field Gradients ◽  
Field Gradients ◽  
Dipole Polarizabilities

Ab initio calculations on a series of trisubstituted amines, phosphines, and arsines are presented at the MP2/6-311G(d,p) level. Specifically, the species studied are XH3, XF3, and X(Me)3, where X = N, P, or As. The influence of the substituents on the proton affinity is analyzed in terms of the charge distribution, its topology, some one-electron properties (dipole moments, electric field gradients), and dipole polarizabilities. An atoms-in-molecules. decomposition of the charge distribution, energetics, and polarizabilities also proves informative. There seems to be no straightforward way of rationalizing the basicities of these compounds on the basis of electrostatic properties (i.e., properties of the charge distribution in the unprotonated bases). However, substituent effects on basicities can be correlated with response properties, such as the molecular (and atoms-in-molecules) polarizability tensors, and the amount of charge that a substituent group or atom donates on protonation. Key words: quantum chemistry, proton affinity, electron density, lone pairs, polarizability, basicity, dipole moment, electric field gradient.

Dipole moments and tautomeric equilibria of some aroylacetanilides

1981 ◽  
Vol 78 ◽  
pp. 155-159 ◽  
Author(s):  
Magdi M. Naoum ◽  
Hakim G. Shinouda ◽  
Ahmed S. Shawali ◽  
Hanna A. Rizk
Keyword(s):  
Dipole Moments ◽  
Tautomeric Equilibria

A Transferable, Polarisable Force Field for Ionic Liquids

2019 ◽  
Author(s):  
Kateryna Goloviznina ◽  
José N. Canongia Lopes ◽  
Margarida Costa Gomes ◽  
Agilio Padua
Keyword(s):  
Ionic Liquids ◽  
Force Field ◽  
Force Fields ◽  
Dipole Moments ◽  
Van Der Waals Interactions ◽  
First Principles Calculations ◽  
Ion Diffusion ◽  
Fixed Integer ◽  
Molecular Compounds ◽  
Induced Dipoles

A general, transferable polarisable force field for molecular simulation of ionic liquids and their mixtures with molecular compounds is developed. This polarisable model is derived from the widely used CL\&P fixed-charge force field that describes most families of ionic liquids, in a form compatible with OPLS-AA, one of the major force fields for organic compounds. Models for ionic liquids with fixed, integer ionic charges lead to pathologically slow dynamics, a problem that is corrected when polarisation effects are included explicitly. In the model proposed here, Drude induced dipoles are used with parameters determined from atomic polarisabilities. The CL\&P force field is modified upon inclusion of the Drude dipoles, to avoid double-counting of polarisation effects. This modification is based on first-principles calculations of the dispersion and induction contributions to the van der Waals interactions, using symmetry-adapted perturbation theory (SAPT) for a set of dimers composed of positive, negative and neutral fragments representative of a wide variety of ionic liquids. The fragment approach provides transferability, allowing the representation of a multitude of cation and anion families, including different functional groups, without need to re-parametrise. Because SAPT calculations are expensive an alternative predictive scheme was devised, requiring only molecular properties with a clear physical meaning, namely dipole moments and atomic polarisabilities. The new polarisable force field, CL\&Pol, describes a broad set set of ionic liquids and their mixtures with molecular compounds, and is validated by comparisons with experimental data on density, ion diffusion coefficients and viscosity. The approaches proposed here can also be applied to the conversion of other fixed-charged force fields into polarisable versions.<br>

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