CASPT2 and CCSD(T) calculations of dipole moments and polarizabilities of acetone in excited states

• Published in: Molecular physics 2012-09, Vol.110 (18), p.2219-2237
• Main Authors: Pašteka, Lukáš F., Melicherčík, Miroslav, Neogrády, Pavel, Urban, Miroslav
• Format: Article
• Language: English
• Subjects: Acetone; Atoms & subatomic particles; CASPT2; CASSCF; CCSD(T); Chemical reactions; Dipole moment; Electric properties; Excitation; excited states; FFPT; finite-field; Gases; Ground state; Grounds; hyperpolarizability; Mathematical analysis; polarizability; Rydberg states; Symmetry
• ISSN: 0026-8976; 1362-3028
• DOI: 10.1080/00268976.2012.668970

The acetone molecule is investigated in its ground state and valence 1,3 n-π*, 1,3 π-π*, and 1,3 σ-π* excited states and Rydberg 1,3 n-3s, 1,3 π-3 , 1,3 n-3p y and 1,3 π-3p y states using the CASSCF, CASPT2, and CCSD(T) methods. Equilibrium geometries of excited states are obtained and their changes with respect to the ground state are discussed. For most excited states the C 2v symmetry of the ground state is lowered to the C s symmetry. A series of valence vertical and adiabatic excitation energies is presented along with excitation energies for Rydberg states. The main body of the paper contains Finite-Field Perturbation Theory (FFPT) calculations of electric properties of the vertically as well as geometry relaxed excited states. Dipole moments of valence excited states decrease significantly upon excitation, being about one half of the ground state dipole moment. Polarizabilities usually change upon excitation much less (increase by about 30%) but hyperpolarizabilities are enhanced up to one or two orders of magnitude. The orientation of the dipole moment is reversed in some vertically excited Rydberg states. Properties of the ground and excited states are discussed considering alterations of the electronic structure and shifts in the geometry.