Charge calculations in molecular mechanics. Part 8 Partial atomic charges from classical calculations

1991 ◽  
Vol 5 (1) ◽  
Author(s):  
RaymondJ. Abraham ◽  
GuyH. Grant ◽  
IanS. Haworth ◽  
PaulE. Smith
Keyword(s):  
Molecular Mechanics ◽  
Atomic Charges ◽  
Partial Atomic Charges ◽  
Charge Calculations

scholarly journals COMPARAÇÃO ENTRE MÉTODOS PARA DETERMINAÇÃO DE CARGAS ATÔMICAS EM SISTEMAS MOLECULARES: A MOLÉCULA N-{N-(PTERINA-7-IL)CARBONILGLICIL}-L-TIROSINA (NNPT)

Química Nova ◽  
2020 ◽  
Author(s):  
Fernanda Botelho ◽  
Roberta Oliveira ◽  
Joyce Almeida ◽  
Tanos França ◽  
Itamar Borges
Keyword(s):  
Dipole Moment ◽  
Atomic Charge ◽  
Basis Sets ◽  
Atomic Charges ◽  
Resonance Effects ◽  
Molecular Systems ◽  
Moment Vector ◽  
Different Types ◽  
Partial Atomic Charges ◽  
Charge Calculations

COMPARISON BETWEEN ATOMIC CHARGE METHODS FOR MOLECULAR SYSTEMS: THE N-{N-(PTERIN-7-YL) CARBONYLGLYCYL}-L-TYROSINE (NNPT) MOLECULE. Selecting a method to compute partial atomic charges is not trivial because different methods usually provide different charge values and there is no consensus on the most useful approach. In this work, Mulliken, MBS, Chelp, Chelpg, MK, Hirshfeld, NPA, DMA and AIM methods were selected to compute atomic charges and electric dipole moment vector of N-{N-(Pterin-7-yl)carbonylglycyl}-L-tyrosine molecule, a ricin inhibitor which has different types of bonds and chemical environments. While MBS and DMA methods provided the most chemically consistent charges according to atomic electronegativity and electron resonance effects criteria, Chelp, Chelpg and MK had the worst performances. Atomic charges and dipole moment calculated by the Hirshfeld method had the smallest magnitudes, a well-known behavior. Despite the differences among atomic charges predicted by all methods, the direction of the dipole moment vector was essentially the same. Further charge calculations using different basis sets and quantum methods indicated that the dependency on this aspect was the highest for Mulliken and Chelp and the lowest for MBS, Hirshfeld and DMA methods. Thus, results point to MBS and DMA as the most suitable methods for computing chemically consistent atomic charges and dipole moment vectors of similar systems for different applications; e.g., molecular dynamics.

scholarly journals Predicting partial atomic charges in siliceous zeolites

2019 ◽  
Vol 277 ◽  
pp. 184-196 ◽  
Author(s):  
Jarod J. Wolffis ◽  
Danny E.P. Vanpoucke ◽  
Amit Sharma ◽  
Keith V. Lawler ◽  
Paul M. Forster
Keyword(s):  
Atomic Charges ◽  
Partial Atomic Charges

scholarly journals Determining Partial Atomic Charges for Liquid Water: Assessing Electronic Structure and Charge Models

2020 ◽  
Author(s):  
Bowen Han ◽  
Christine Isborn ◽  
Liang Shi
Keyword(s):  
Electronic Structure ◽  
Dipole Moment ◽  
Charge Transfer ◽  
Liquid Water ◽  
Quantum Chemical ◽  
Water Dimer ◽  
Atomic Charges ◽  
Molecular Dipole ◽  
Molecular Dipole Moment ◽  
Partial Atomic Charges

Partial atomic charges provide an intuitive and efficient way to describe the charge distribution and the resulting intermolecular electrostatic interactions in liquid water. Many charge models exist and it is unclear which model provides the best assignment of partial atomic charges in response to the local molecular environment. In this work, we systematically scrutinize various electronic structure methods and charge models (Mulliken, Natural Population Analysis, CHelpG, RESP, Hirshfeld, Iterative Hirshfeld, and Bader) by evaluating their performance in predicting the dipole moments of isolated water, water clusters, and liquid water as well as charge transfer in the water dimer and liquid water. Although none of the seven charge models is capable of fully capturing the dipole moment increase from isolated water (1.85 D) to liquid water (about 2.9 D), the Iterative Hirshfeld method performs best for liquid water, reproducing its experimental average molecular dipole moment, yielding a reasonable amount of intermolecular charge transfer, and showing modest sensitivity to the local water environment. The performance of the charge model is dependent on the choice of the density functional and the quantum treatment of the environment. The computed molecular dipole moment of water generally increases with the percentage of the exact Hartree-Fock exchange in the functional, whereas the amount of charge transfer between molecules decreases. For liquid water, including two full solvation shells of surrounding water molecules (within about 5.5 A of the central water) in the quantum-chemical calculation converges the charges of the central water molecule. Our final pragmatic quantum-chemical charge assigning protocol for liquid water is the Iterative Hirshfeld method with M06-HF/aug-cc-pVDZ and a quantum region cutoff radius of 5.5 A.<br>

Cooperative Hydrogen-Bonding Effects in a Water Square:  A Single-Crystal Neutron and Partial Atomic Charges and Hardness Analysis Study

2005 ◽  
Vol 127 (31) ◽  
pp. 11063-11074 ◽  
Author(s):  
David R. Turner ◽  
Marc Henry ◽  
Clive Wilkinson ◽  
Garry J. McIntyre ◽  
Sax A. Mason ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Single Crystal ◽  
Atomic Charges ◽  
Analysis Study ◽  
Partial Atomic Charges ◽  
Cooperative Hydrogen Bonding

X-Ray photoelectron spectroscopy of monosubstituted perfluorobenzenes

1977 ◽  
Vol 55 (8) ◽  
pp. 1279-1284 ◽  
Author(s):  
Barry C. Trudell ◽  
S. James W. Price
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Binding Energies ◽  
Photoelectron Spectra ◽  
Atomic Charges ◽  
X Ray ◽  
Sophisticated Analysis ◽  
Charge Calculations

The gas phase X-ray photoelectron spectra, XPS, were observed for the series C6F5X (X = F, Cl, I, Br, H). Binding energies were determined from the spectra using the ESCAPLOT Program. Charge calculations were carried out using Equalization of Electronegativity, CNDO/2, and ACHARGE approaches on each molecule. The more sophisticated analysis leads to the following equation correlating the (C 1s) binding energies and the atomic charges qi[Formula: see text]

Approaches to charge calculations in molecular mechanics

1982 ◽  
Vol 3 (3) ◽  
pp. 407-416 ◽  
Author(s):  
Raymond J. Abraham ◽  
Lee Griffiths ◽  
Philip Loftus
Keyword(s):  
Molecular Mechanics ◽  
Charge Calculations
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