CI Calculations of Vertical Excitation Energies and Oscillator Strengths for Rydberg and Valence States of Molecules

Large-scale multi-reference single and double-excitation configuration interaction (MRD-CI) calculations are employed for the study of the isovalent compounds H2CNH, H2SiNH, H2CPH, and H2SiPH in their ground state equilibrium geometry. The dipole moments and charge distributions are given. The vertical excitation energies to the intra-valence states 3.1(n, π*) and 3.1(π, π*) and to the first members of the Rydberg series originating from n and π MO's respectively are predicted; the first two ionization potentials and the Rydberg term values are also calculated. In H2CNH, mixing of Rydberg and valence-shell states with CN stretching is analyzed. The trends in relative stability of electronic and ionized states can be directly related to increased orbital stability of n relative to π as soon as a first-row constituent is replaced by a second-row atom. The calculations explain the diffuse character of the uv spectrum of imines; they treat the molecules H2SiNH and H2SiPH for the first time and present a large number of data for all four molecules which can serve as a basis for future experimental investigations on these and related compounds.

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Vertical excitation energies to valence states of DMS and DMSO

Theoretical Chemistry Accounts ◽

10.1007/s00214-007-0339-x ◽

2007 ◽

Vol 118 (3) ◽

pp. 527-531 ◽

Cited By ~ 6

Author(s):

V. Pérez Mondéjar ◽

M. J. Yusá ◽

I. García Cuesta ◽

A. M. J. Sánchez de Merás ◽

J. Sánchez-Marín

Keyword(s):

Excitation Energies ◽

Vertical Excitation ◽

Valence States ◽

Vertical Excitation Energies

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The electronic structure of the first row hydrides BH, CH, NH, OH and FH II. Excited states

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1959.0032 ◽

1959 ◽

Vol 249 (1258) ◽

pp. 402-413 ◽

Cited By ~ 32

Keyword(s):

Electronic Structure ◽

Excited States ◽

Electron Correlation ◽

Ground States ◽

Oscillator Strengths ◽

Excitation Energies ◽

Vertical Excitation ◽

Experimental Values ◽

Vertical Excitation Energies ◽

Dipole Length

Previous calculations on the ground states of the hydrides are extended to include the stable excited states. The ab initio orbital calculations predict vertical excitation energies which differ from the experimental values by as much as 2eV. However, when allowance is made for the effects of atomic electron correlation all errors in the calculated excitation energies become less than 0·2eV. The locations of excited states of different multiplicities from those of the ground states are predicted to within this accuracy. The oscillator strengths of allowed transitions from the ground states are calculated using both the dipole-length and dipole-velocity formulae. The dipole-length values are in fair agreement with the only experimental value available (for OH 2 ll → 2 ∑ + ), whereas the dipole-velocity values are much too large. Possible improvements in the accuracy of the calculations are discussed.

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