Adiabatic perturbation theory for two-component systems with one heavy component

Requist, Ryan (2025) Adiabatic perturbation theory for two-component systems with one heavy component. Physical Review B, 111 (2). ISSN 2469-9950

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Abstract

Perturbation theory with respect to the kinetic energy of the heavy component of a two-component quantum system is introduced. An effective Hamiltonian that is accurate to second order in the inverse heavy mass is derived. It contains a new form of kinetic energy operator with a Hermitian mass tensor and a complex-valued vector potential. All of the potentials in the effective Hamiltonian can be expressed in terms of covariant derivatives and a resolvent operator. The most salient application of the theory is to systems of electrons and nuclei. The accuracy of the theory is verified numerically in a model diatomic molecule and analytically in a vibronic coupling model.

Item Type:	Article
Uncontrolled Keywords:	Condensed matter physics; non-adiabatic effects
Subjects:	NATURAL SCIENCES > Physics NATURAL SCIENCES > Physics > Condensed Matter Physics
Divisions:	Theoretical Physics Division
Depositing User:	Ema Buhin Šaler
Date Deposited:	26 Feb 2026 12:11
URI:	http://fulir.irb.hr/id/eprint/11273
DOI:	10.1103/PhysRevB.111.024311

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