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Title: Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute

Abstract

We present a method for computing the electrostatic component of the solvation free energy, {Delta}G{sup el}, of a solute molecule in the presence of solvent modeled as a dielectric continuum. The method is based on an integral form of Poisson`s equation which is solved to obtain a distribution of induced polarization charge at the solute-solvent dielectric interface. The solution of Poisson`s equation is obtained by application of a boundary element procedure. The method is tested by comparing its predictions of {Delta}G{sup el} to exact values for several model problems. The method is then used in a variety of contexts to assess its qualitative prediction ability. It is first combined with a molecular mechanics treatment of the solute to evaluate the effects of aqueous solvent on the conformational equilibria of several small molecules of interest-these are N-methyl acetamide and alanine dipeptide. For both molecules dielectric continuum solvation predicts torsional free energies of solvation that are in accord with other more complete treatments of solvation. The method is then combined with ab initio and semi-empirical molecular orbital theory for the solute. Self consistent reaction field calculations (SCRF) are performed to evaluate the correlation is in general very good. Relative agreement with experimentmore » is best for ions where electrostatics predominate and worst for non-polar neutral molecules were electrostatics are minor. Semi-empirical configuration interaction SCRF calculations are also performed in the presence of solvent in order to determine ground-to-excited state absorption energy shifts for formaldehyde and indole mine ground-to-excited state absorption energy shifts for formaldehyde and indole when placed in water. We find a rough correlation between transition energy shifts and the dipole moments of the initial and final states involved in the transition.« less

Authors:
 [1]; ;  [2]
  1. Frederick Cancer Research and Development Center, MD (United States)
  2. Los Alamos National Lab., NM (United States)
Publication Date:
OSTI Identifier:
447549
Report Number(s):
CONF-960343-
TRN: 97:005446
Resource Type:
Conference
Resource Relation:
Conference: 2. international congress on theoretical chemical physics, New Orleans, LA (United States), 9-13 Mar 1996; Other Information: PBD: 1996; Related Information: Is Part Of Second international congress on theoretical chemical physics - ICTCP II; PB: 90 p.
Country of Publication:
United States
Language:
English
Subject:
40 CHEMISTRY; 66 PHYSICS; FREE ENERGY; CALCULATION METHODS; SOLVENTS; MOLECULAR STRUCTURE; ELECTRONIC STRUCTURE; POISSON EQUATION

Citation Formats

Tawa, G J, Pratt, L R, and Martin, R L. Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute. United States: N. p., 1996. Web.
Tawa, G J, Pratt, L R, & Martin, R L. Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute. United States.
Tawa, G J, Pratt, L R, and Martin, R L. 1996. "Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute". United States.
@article{osti_447549,
title = {Energetics and structure in solvent: A dielectric continuum model of solvation combined with molecular mechanics, Ab Initio, and Semi-empirical molecular orbital treatments of the solute},
author = {Tawa, G J and Pratt, L R and Martin, R L},
abstractNote = {We present a method for computing the electrostatic component of the solvation free energy, {Delta}G{sup el}, of a solute molecule in the presence of solvent modeled as a dielectric continuum. The method is based on an integral form of Poisson`s equation which is solved to obtain a distribution of induced polarization charge at the solute-solvent dielectric interface. The solution of Poisson`s equation is obtained by application of a boundary element procedure. The method is tested by comparing its predictions of {Delta}G{sup el} to exact values for several model problems. The method is then used in a variety of contexts to assess its qualitative prediction ability. It is first combined with a molecular mechanics treatment of the solute to evaluate the effects of aqueous solvent on the conformational equilibria of several small molecules of interest-these are N-methyl acetamide and alanine dipeptide. For both molecules dielectric continuum solvation predicts torsional free energies of solvation that are in accord with other more complete treatments of solvation. The method is then combined with ab initio and semi-empirical molecular orbital theory for the solute. Self consistent reaction field calculations (SCRF) are performed to evaluate the correlation is in general very good. Relative agreement with experiment is best for ions where electrostatics predominate and worst for non-polar neutral molecules were electrostatics are minor. Semi-empirical configuration interaction SCRF calculations are also performed in the presence of solvent in order to determine ground-to-excited state absorption energy shifts for formaldehyde and indole mine ground-to-excited state absorption energy shifts for formaldehyde and indole when placed in water. We find a rough correlation between transition energy shifts and the dipole moments of the initial and final states involved in the transition.},
doi = {},
url = {https://www.osti.gov/biblio/447549}, journal = {},
number = ,
volume = ,
place = {United States},
year = {1996},
month = {12}
}

Conference:
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