高精度量子化学計算手法の解析的エネルギー微分法の開発

抄録

Accurate quantum chemical methods are reliable due to their rigorous treatment of the wavefunction. However, it is known that optimizing molecular geometries using these methods is not straightforward, owing to the lack of analytic derivatives of the computed energy. This account briefly describes the analytic derivative theory of variational and non-variational methods as well as the multiconfiguration and multireference methods. For non-variational methods, we utilize the Z-vector or Lagrangian methods to avoid explicitly computing derivatives of wavefunction parameters. The developed method is applied to determining minimum energy structures on adiabatic potential energy surfaces and crossings between them (conical intersections). The selected examples demonstrate that the developed methods are useful for accurately describing (photo)chemical properties.