Recently, we have developed a novel Polarizable Continuum Model (PCM), which includes both surface and volume polarization of the dielectric medium (pure SVPE scheme), designed for the Quantum Monte Carlo (QMC) treatment of the solute. In particular, the treatment of volume polarization, due to quantum mechanical penetration of the solute charge density in the solvent domain, is based on quantum Monte Carlo techniques. The method allows to accurately solve Poisson's equation of the solvation model coupled with the Schrödinger equation for the solute [1,2,3]. The present model has been now extended to treat the effects of solvation in solute vertical electronic transitions and to the search of the solute equilibrium geometry in the excited states. For the first case, here we show the results of our study performed on fast n → pi* and pi → pi* vertical transitions of s-trans- acrolein in water [4]. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we have added a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. The calculated solvatochromic shifts are properly described. For the second case, we start from recent advances made to carry out the ground- and excited-state geometry optimization within QMC [5]. For the present purpose, we have extended the calculation of the forces to include solvent e_ects through our QMC implementation of PCM [6]. We show results, performed at the variational Monte Carlo level, on the excited-state geometry optimization of some small organic molecules in water solution and we make a comparison with the more widely used TDDFT and CASPT2 methods. [1] C. Amovilli, C. Filippi, F. M. Floris, J. Phys. Chem. B (2006) 110 26225. [2] C. Amovilli, C. Filippi, F. M. Floris, J. Chem. Phys. (2008) 129 244106. [3] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2012) 137 075102. [4] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2014) 140 034109. [5] R. Guareschi, C. Filippi, J. Chem. Theor. Comput. (2013) 9 5513. [6] R. Guareschi, F. M. Floris, C. Amovilli, C. Filippi, in preparation (2014).

Poster P15: Excited states of molecular solutes with Quantum Monte Carlo: vertical transition and geometry optimization

F. M. Floris
;
C. Amovilli;
2014-01-01

Abstract

Recently, we have developed a novel Polarizable Continuum Model (PCM), which includes both surface and volume polarization of the dielectric medium (pure SVPE scheme), designed for the Quantum Monte Carlo (QMC) treatment of the solute. In particular, the treatment of volume polarization, due to quantum mechanical penetration of the solute charge density in the solvent domain, is based on quantum Monte Carlo techniques. The method allows to accurately solve Poisson's equation of the solvation model coupled with the Schrödinger equation for the solute [1,2,3]. The present model has been now extended to treat the effects of solvation in solute vertical electronic transitions and to the search of the solute equilibrium geometry in the excited states. For the first case, here we show the results of our study performed on fast n → pi* and pi → pi* vertical transitions of s-trans- acrolein in water [4]. To perform calculations in a non-equilibrium solvation regime for the solute excited state, we have added a correction to the global dielectric polarization charge density, obtained self consistently with the solute ground-state wave function by assuming a linear-response scheme. The calculated solvatochromic shifts are properly described. For the second case, we start from recent advances made to carry out the ground- and excited-state geometry optimization within QMC [5]. For the present purpose, we have extended the calculation of the forces to include solvent e_ects through our QMC implementation of PCM [6]. We show results, performed at the variational Monte Carlo level, on the excited-state geometry optimization of some small organic molecules in water solution and we make a comparison with the more widely used TDDFT and CASPT2 methods. [1] C. Amovilli, C. Filippi, F. M. Floris, J. Phys. Chem. B (2006) 110 26225. [2] C. Amovilli, C. Filippi, F. M. Floris, J. Chem. Phys. (2008) 129 244106. [3] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2012) 137 075102. [4] F. M. Floris, C. Filippi, C. Amovilli, J. Chem. Phys. (2014) 140 034109. [5] R. Guareschi, C. Filippi, J. Chem. Theor. Comput. (2013) 9 5513. [6] R. Guareschi, F. M. Floris, C. Amovilli, C. Filippi, in preparation (2014).
2014
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11568/960663
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