Potentials of mean force with ab initio mixed Hamiltonian models of solvation

Michel Dupuis, G. K. Schenter, B. G. Garrett, E. E. Arcia

Research output: Contribution to journalArticle

10 Citations (Scopus)

Abstract

We give an account of a computationally tractable and efficient procedure for the calculation of potentials of mean force using mixed Hamiltonian models of electronic structure where quantum subsystems are described with computationally intensive ab initio wavefunctions. The mixed Hamiltonian is mapped into an all-classical Hamiltonian that is amenable to a thermodynamic perturbation treatment for the calculation of free energies. A small number of statistically uncorrelated (solute-solvent) configurations are selected from the Monte Carlo random walk generated with the all-classical Hamiltonian approximation. Those are used in the averaging of the free energy using the mixed quantum/classical Hamiltonian. The methodology is illustrated for the micro-solvated SN2 substitution reaction of methyl chloride by hydroxide. We also compare the potential of mean force calculated with the above protocol with an approximate formalism, one in which the potential of mean force calculated with the all-classical Hamiltonian is simply added to the energy of the isolated (non-solvated) solute along the reaction path. Interestingly the latter approach is found to be in semi-quantitative agreement with the full mixed Hamiltonian approximation.

Original languageEnglish
Pages (from-to)173-183
Number of pages11
JournalJournal of Molecular Structure: THEOCHEM
Volume632
DOIs
Publication statusPublished - Aug 1 2003

Fingerprint

Methyl Chloride
Hamiltonians
Solvation
Thermodynamics
solvation
solutes
free energy
methyl chloride
approximation
random walk
hydroxides
Free energy
methodology
substitutes
formalism
electronic structure
perturbation
thermodynamics
configurations
Wave functions

Keywords

  • Hamiltonian models
  • Mixed Hamiltonians
  • Potential of mean force
  • Solute
  • Solvent

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics
  • Atomic and Molecular Physics, and Optics

Cite this

Potentials of mean force with ab initio mixed Hamiltonian models of solvation. / Dupuis, Michel; Schenter, G. K.; Garrett, B. G.; Arcia, E. E.

In: Journal of Molecular Structure: THEOCHEM, Vol. 632, 01.08.2003, p. 173-183.

Research output: Contribution to journalArticle

Dupuis, Michel ; Schenter, G. K. ; Garrett, B. G. ; Arcia, E. E. / Potentials of mean force with ab initio mixed Hamiltonian models of solvation. In: Journal of Molecular Structure: THEOCHEM. 2003 ; Vol. 632. pp. 173-183.
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