Conditional Wave Function Theory: A Unified Treatment of Molecular Structure and Nonadiabatic Dynamics.

Abstract

A conditional wave function theory is presented as a unified approach for describing both equilibrium molecular structure and nonadiabatic dynamics in correlated electron-ion systems. By decomposing the many-body wave function into lower-dimensional conditional slices, the full interacting wave function of a closed system is reformulated in a tractable manner. A variational ansatz constructed from these conditional slices was validated against the structural and time-dependent response properties of the hydrogen molecule. The framework was further extended to time-dependent conditional wave functions, enabling treatment of nonequilibrium phenomena such as strong-field ionization, laser-induced proton transfer, and nuclear quantum effects near conical intersections. The approach is positioned as a foundation for ab initio molecular simulations across equilibrium and nonequilibrium regimes.

Mechanism

The many-body wave function is decomposed into lower-dimensional conditional slices, allowing a variational treatment that captures both structural and dynamical properties of correlated electron-ion systems within a single theoretical framework.