Semi-empirical valence bond models of conjugated alkenes with donor and acceptor substituents

2001 ◽  
Vol 3 (12) ◽  
pp. 2419-2423 ◽  
Author(s):  
Jian Wu ◽  
David L. Cooper
Keyword(s):  
Valence Bond ◽  
Empirical Valence Bond ◽  
Donor And Acceptor ◽  
Semi Empirical

scholarly journals An Investigation into the Approximations Used in Wave Packet Molecular Dynamics for the Study of Warm Dense Matter

Plasma ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 294-308
Author(s):  
William A. Angermeier ◽  
Thomas G. White
Keyword(s):  
Molecular Dynamics ◽  
Wave Packet ◽  
Hydrogen Plasma ◽  
Valence Bond ◽  
Dense Matter ◽  
Basis Set ◽  
Warm Dense Matter ◽  
Scaling Parameters ◽  
Oppenheimer Approximation ◽  
Semi Empirical

Wave packet molecular dynamics (WPMD) has recently received a lot of attention as a computationally fast tool with which to study dynamical processes in warm dense matter beyond the Born–Oppenheimer approximation. These techniques, typically, employ many approximations to achieve computational efficiency while implementing semi-empirical scaling parameters to retain accuracy. We investigated three of the main approximations ubiquitous to WPMD: a restricted basis set, approximations to exchange, and the lack of correlation. We examined each of these approximations in regard to atomic and molecular hydrogen in addition to a dense hydrogen plasma. We found that the biggest improvement to WPMD comes from combining a two-Gaussian basis with a semi-empirical correction based on the valence-bond wave function. A single parameter scales this correction to match experimental pressures of dense hydrogen. Ultimately, we found that semi-empirical scaling parameters are necessary to correct for the main approximations in WPMD. However, reducing the scaling parameters for more ab-initio terms gives more accurate results and displays the underlying physics more readily.

scholarly journals Uncovering the Role of Key Active Site Side Chains in Catalysis: An Extended Brønsted Relationship for Substrate Deprotonation Catalysed by Wild-Type and Variants of Triosephosphate Isomerase

2019 ◽  
Author(s):  
Yashraj S. Kulkarni ◽  
Tina L. Amyes ◽  
John Richard ◽  
Shina Caroline Lynn Kamerlin
Keyword(s):  
Active Site ◽  
Triosephosphate Isomerase ◽  
Valence Bond ◽  
Side Chains ◽  
Wild Type ◽  
Empirical Valence Bond

Manuscript and supporting information outlining an analysis of an extended Brønsted relationship obtained from empirical valence bond simulations of substrate deprotonation catalyzed by wild-type and mutant variants of triosephosphate isomerase.

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