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Title: Time-dependent non-equilibrium dielectric response in QM/continuum approaches

The Polarizable Continuum Models (PCMs) are some of the most inexpensive yet successful methods for including the effects of solvation in quantum-mechanical calculations of molecular systems. However, when applied to the electronic excitation process, these methods are restricted to dichotomously assuming either that the solvent has completely equilibrated with the excited solute charge density (infinite-time limit), or that it retains the configuration that was in equilibrium with the solute prior to excitation (zero-time limit). This renders the traditional PCMs inappropriate for resolving time-dependent solvent effects on non-equilibrium solute electron dynamics like those implicated in the instants following photoexcitation of a solvated molecular species. To extend the existing methods to this non-equilibrium regime, we herein derive and apply a new formalism for a general time-dependent continuum embedding method designed to be propagated alongside the solute’s electronic degrees of freedom in the time domain. Given the frequency-dependent dielectric constant of the solvent, an equation of motion for the dielectric polarization is derived within the PCM framework and numerically integrated simultaneously with the time-dependent Hartree fock/density functional theory equations. Results for small molecular systems show the anticipated dipole quenching and electronic state dephasing/relaxation resulting from out-of-phase charge fluctuations in the dielectric and embeddedmore » quantum system.« less
Authors:
; ;  [1] ;  [2]
  1. Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)
  2. Dipartimento di Chimica e Chimica Industriale, Università di Pisa, Via Risorgimento 35, 56126 Pisa (Italy)
Publication Date:
OSTI Identifier:
22416009
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 3; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHARGE DENSITY; DEGREES OF FREEDOM; DENSITY FUNCTIONAL METHOD; DIELECTRIC MATERIALS; DIPOLES; ELECTRONS; EQUATIONS OF MOTION; EXCITATION; FLUCTUATIONS; FREQUENCY DEPENDENCE; HARTREE-FOCK METHOD; PERMITTIVITY; POLARIZATION; QUANTUM MECHANICS; QUANTUM SYSTEMS; RELAXATION; SOLUTES; SOLVATION; SOLVENTS; TIME DEPENDENCE