Excitation energies from time-dependent generalized valence bond method
A generalized valence bond perfect-pairing (GVBPP) wavefunction has been extensively used in computational chemistry methods due to its multiconfigurational character, which captures in an inexpensive way static electron correlation. GVB-PP has been mostly applied to ground states and not much is known about its performance in predicting electronic spectra of molecules. Here, we present the formalism based on the time-dependent linear response theory which provides excitation energies from the GVB-PP ground-state wavefunction. The accuracy of the excitation energy dissociation curves parallels that of the TD-HF method around groundstate equilibrium geometries of the investigated molecules. For stretched-bond molecules, when TD-HF breaks down, the proposed TD-GVB method remains reliable. TD-GVB may therefore serve as a useful and inexpensive tool for exploring potential energy surfaces of excited states of molecules.
KeywordsGeneralized valence bond Time-dependent linear response Excitation energy
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