First-order derivative couplings between excited states from adiabatic TDDFT response theory

Journal Article · Sat Feb 14 04:00:00 EST 2015 · Journal of Chemical Physics

DOI:https://doi.org/10.1063/1.4906941· OSTI ID:22416099

Ou, Qi; Bellchambers, Gregory D.; Furche, Filipp ^[1]

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1. Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, California 92697-2025 (United States)

We present a complete derivation of derivative couplings between excited states in the framework of adiabatic time-dependent density functional response theory. Explicit working equations are given and the resulting derivative couplings are compared with derivative couplings from a pseudo-wavefunction ansatz. For degenerate excited states, i.e., close to a conical intersection (CI), the two approaches are identical apart from an antisymmetric overlap term. However, if the difference between two excitation energies equals another excitation energy, the couplings from response theory exhibit an unphysical divergence. This spurious behavior is a result of the adiabatic or static kernel approximation of time-dependent density functional theory leading to an incorrect analytical structure of the quadratic response function. Numerical examples for couplings close to a CI and for well-separated electronic states are given.

• OSTI ID: 22416099
• Journal Information: Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 6 Vol. 142; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
ADIABATIC APPROXIMATION
COMPARATIVE EVALUATIONS
DENSITY FUNCTIONAL METHOD
EQUATIONS
EXCITATION
EXCITED STATES
KERNELS
RESPONSE FUNCTIONS
TIME DEPENDENCE
WAVE FUNCTIONS