Excitation Energies in Solution: The Fully Polarizable QM/MM/PCM Method

Abstract

We present the theory and an implementation of the combined quantum mechanics/molecular mechanics/polarizable dielectric continuum (QM/MM/PCM) method. This is a fully polarizable layered model designed for effective inclusion of a medium in a quantum-mechanical calculation. The short-range part of the solvent electrostatic potential is described by an atomistic model while the long-range part of this potential is described by a dielectric continuum. The QM/MM/PCM method has been implemented in combination with QM linear response techniques allowing for the assessment of, e.g., vertical electronic excitation energies and linear dipole-dipole polarizabilities, in all cases using a nonequilibrium formulation of the environmental response. The model is general, but is here implemented for the case of density functional theory. Numerical examples are given for solvatochromic shifts relating to a set of organic molecules in aqueous solution. We find in general the QM/MM/PCM interface to exhibit a faster convergence with respect to the system size as compared to the use of QM/MM only.

Four-Component Relativistic Calculations in Solution with the Polarizable Continuum Model of Solvation: Theory, Implementation, and Application to the Group 16 Dihydrides H2X (X = O, S, Se, Te, Po)

“…The second-order DouglasKroll-Hess (DKH2) in spin-free form, has also been applied 40 In all aforementioned studies, bulk solvent effects, described by use of a continuum model such as COSMO, were found to be extremely important in order to achieve a qualitatively accurate description of the phenomena of interest. Remarkably, such a conclusion was reached for aprotic 23 Due to the theoretical similarity between the PCM, more refined polarizable molecular mechanics 13,14 and even three-layer methodologies [15][16][17] , this work constitutes a starting point for more accurate models for the inclusiont of environment effects in computational procedures based on relativistic Hamiltonians.…”

“…QM/MM and continuum methods can also be combined [15][16][17] , to achieve a faithful, yet cost-effective strategy to reproduce solvent effects.…”

Toward high-throughput predictions of the hydration free energies of small organic molecules from first principles

“…Over the past three decades, molecular simulation has been routinely used to study solvent effects and achieve a great success [70,71]. Since the solvation free energy is a quantity connecting two different thermodynamic states, molecular simulation requires efficient sampling of the microstates over various thermodynamic pathways [72,73].…”

Implementation of the CCSD-PCM linear response function for frequency dependent properties in solution: Application to polarizability and specific rotation

“…[19][20][21][22] In this work, I present the first implementation of the frequency-dependent linear response function for the CCSD-PCM method, and applications to the calculation of molecular electric polarizability and specific rotation. The numerical results for the polarizability are used for theoretical comparisons between methods.…”