Pseudospectral localized Mo/ller–Plesset methods: Theory and calculation of conformational energies

1995 ◽  
Vol 103 (4) ◽  
pp. 1481-1490 ◽  
Author(s):  
Robert B. Murphy ◽  
Michael D. Beachy ◽  
Richard A. Friesner ◽  
Murco N. Ringnalda
Keyword(s):  
Localized Mo ◽  
Conformational Energies

scholarly journals Conformational energies and equilibria of cyclic dinucleotides in vacuo and in solution: computational chemistry vs. NMR experiments

2021 ◽  
Author(s):  
Ondrej Gutten ◽  
Petr Jurečka ◽  
Zahra Aliakbar Tehrani ◽  
Miloš Buděšínský ◽  
Jan Řezáč ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Quantum Mechanics ◽  
Computational Chemistry ◽  
Computational Error ◽  
Cyclic Dinucleotides ◽  
Error Bars ◽  
Conformational Energies

Computational “error bars” for modelling cyclic dinucleotides – NMR experiment vs. quantum mechanics and molecular dynamics.

A pairwise additivity scheme for conformational energies of substituted ethanes

1975 ◽  
Vol 343 (1632) ◽  
pp. 1-10 ◽  
Keyword(s):  
Large Deviations ◽  
Ab Initio ◽  
Dihedral Angle ◽  
Molecular Orbital ◽  
Methyl Groups ◽  
Molecular Orbital Calculations ◽  
Linear Combinations ◽  
Strongly Interacting ◽  
Conformational Energies

Ab initio molecular orbital calculations are used to explore additivity in the conformational energies of poly-substituted ethanes in terms of conformational energies of ethane and appropriate mono- and 1,2-di-substituted derivatives. Such relations would allow complex calculations for poly-substituted ethanes to be replaced by much simpler ones on a small number of parent molecules. General expressions for the linear combinations are derived from the assumption that interactions between vicinal substituents are pairwise additive and depend only on the vicinal dihedral angle. The additivity scheme is tested for 15 ethanes, di-, tri- or tetrasubstituted by cyano and methyl groups and for a smaller number of fluoroethanes. Additivity applies to within 0.1- 0.3 k J mol -1 in the methylethanes and mostly to within about 0.7- 0.8 kJ mol -1 in cyanoethanes. Large deviations are found among the geminally substituted fluoroethanes. It is suggested that the additivity approximation is most successful in the absence of strongly interacting geminal groups. Predictions are made of conformational energies of ten hexa(cyano- and methyl-) substituted ethanes.

Conformational features of bisphenol-A polycarbonate

1985 ◽  
Vol 63 (1) ◽  
pp. 103-110 ◽  
Author(s):  
P. R. Sundararajan
Keyword(s):  
Bisphenol A ◽  
Repeat Unit ◽  
Methyl Groups ◽  
Bisphenol A Polycarbonate ◽  
Carbonate Group ◽  
Torsion Angles ◽  
Thermal Crystallization ◽  
Lennard Jones ◽  
Empirical Force Field ◽  
Conformational Energies

Conformational energies have been estimated for the segments of the bisphenol polycarbonate chain, using the Lennard–Jones and Hill's empirical force field type of functions. It is found that the conformation of the carbonate group, defined by the torsion angle ζ, is restricted to the range of 45° to 65°. The rotations χ and χ′ of the methyl groups also show similar limited flexibility. However, accessible conformations of the diphenyl propane (DPP) segment, defined by torsion angles [Formula: see text] and ψ, span a wide area of the [Formula: see text] surface, with the restriction that the rotations [Formula: see text] and ψ be synchronized such that [Formula: see text] or 270°. These features explain the slow thermal crystallization behaviour of the polycarbonate chains. The variability of the conformations of the repeat unit is illustrated with a series of figures.

A Comparison of the ab Initio Calculated and Experimental Conformational Energies of Alkylcyclohexanes

2000 ◽  
Vol 77 (5) ◽  
pp. 661 ◽  
Author(s):  
Marc L. Kasner ◽  
Fillmore Freeman ◽  
Zufan M. Tsegai ◽  
Warren J. Hehre
Keyword(s):  
Ab Initio ◽  
Conformational Energies
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