Accurately Reproducing Ab Initio Electrostatic Potentials with Multipoles and Fragmentation

2009 ◽  
Vol 113 (39) ◽  
pp. 10527-10533 ◽  
Author(s):  
Hai-Anh Le ◽  
Adrian M. Lee ◽  
Ryan P. A. Bettens
Keyword(s):  
Ab Initio ◽  
Electrostatic Potentials

Anomalous stabilizing and destabilizing effects in some cyclic π-electron systems

1993 ◽  
Vol 71 (8) ◽  
pp. 1123-1127 ◽  
Author(s):  
Peter Politzer ◽  
M. Edward Grice ◽  
Jane S. Murray ◽  
Jorge M. Seminario
Keyword(s):  
Ab Initio ◽  
Lone Pair ◽  
Electrostatic Potentials ◽  
Electron Delocalization ◽  
Isodesmic Reaction ◽  
Computational Studies ◽  
Electron Systems ◽  
Molecular Electrostatic Potentials ◽  
Lone Pairs

Ab initio computational studies have been carried out for three molecules that are commonly classed as antiaromatic: cyclobutadiene (1), 1,3-diazacyclobutadiene (7), and 1,4-dihydropyrazine (6). Their dinitro and diamino derivatives were also investigated. Stabilizing or destabilizing energetic effects were quantified by means of the isodesmic reaction procedure at the MP2/6-31G*//HF/3-21G level, and calculated molecular electrostatic potentials (HF/STO-5G//HF/3-21G) were used as a probe of electron delocalization. Our results do not show extensive delocalization in the π systems of any one of the three parent molecules. The destabilization found for 1 and 7 is attributed primarily to strain and to repulsion between the localized π electrons in the C=C and C=N bonds, respectively. However, 6 is significantly stabilized, presumably due to limited delocalization of the nitrogen lone pairs. NH2 groups are highly stabilizing, apparently because of lone pair delocalization. NO2 is neither uniformly stabilizing nor destabilizing.

Calculation of electrostatic potentials and fields inside zeolite cavities

1988 ◽  
Vol 53 (10) ◽  
pp. 2308-2319 ◽  
Author(s):  
János G. Ángyán ◽  
György Ferenczy ◽  
Péter Nagy ◽  
Gábor Náray-Szabó
Keyword(s):  
Ab Initio ◽  
Lone Pair ◽  
Electrostatic Potentials ◽  
Basis Set ◽  
Mean Deviation ◽  
Minimal Basis ◽  
Approximate Methods ◽  
Monopole Approximation ◽  
Van Der Waals Surface ◽  
Modified Formula

We present a modification of our bond increment method for the calculation of molecular electrostatic potentials and fields inside zeolite cavities. Introducing a variant of the Mulliken approximation for the off-diagonal matrix elements of the potential and optimizing the parameters of the modified formula, we achieved much better agreement with ab initio STO-3G minimal basis set results than with the original version. For a representative set of 10 small molecules the standard mean deviation between potentials calculated on the van der Waals surface with the ab initio and approximate methods is 9·1 kJ/mol. The relative error decreases from 21 to 9 per cent for the lone-pair regions of molecules modelling zeolite cavities. Applying the modified bond increment method for a realistic faujausite model we have found that the potential and field are almost exclusively of long-range origin. This means that, if using appropriate atomic charges, the monopole approximation gives correct results for electrostatic potentials and fields inside zeolite cavities.

Ab initio calculation of electrostatic potentials for C60 and C80

2020 ◽  
Vol 53 (3) ◽  
pp. 035102
Author(s):  
Xiaokai Xu ◽  
Yan Zhang ◽  
Bowen Li ◽  
Ximeng Chen
Keyword(s):  
Ab Initio ◽  
Ab Initio Calculation ◽  
Electrostatic Potentials

Ab initio counterpart of infrared atomic charges. Comparison with charges obtained from electrostatic potentials

1988 ◽  
Vol 151 (4-5) ◽  
pp. 397-402 ◽  
Author(s):  
M.N. Ramos ◽  
M. Gussoni ◽  
C. Castiglioni ◽  
G. Zerbi
Keyword(s):  
Ab Initio ◽  
Electrostatic Potentials ◽  
Atomic Charges

On the Calculation of the Electrostatic Potentials at the Nuclei in the Point-charge Approximation

1983 ◽  
Vol 38 (3) ◽  
pp. 308-312 ◽  
Author(s):  
Z. B. Maksić ◽  
K. Rupnik
Keyword(s):  
Ab Initio ◽  
Point Charge ◽  
Atomic Charge ◽  
Electrostatic Potentials ◽  
Molecular Properties ◽  
Atomic Charges ◽  
Self Consistent

Abstract It is shown that the concept of atomic charge in molecules is a useful tool in studying electrostatic potentials at the nuclei which in turn are closely related to a number of molecular properties. Calculations executed on a selected set of widely different compounds provide extensive evidence that the semiempirical SCC-MO (self-consistent charge) atomic charges are equally successful in this respect as the ab initio DZ ones.

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