Conical intersections directly mediate the internal energy conversion in photoinduced processes in a wide range of chemical and biological systems. Because of the Brillouin theorem, many conventional electronic structure methods, including configuration interaction with single excitations from a Hartree-Fock reference and time-dependent density functional theory in either the linear response approximation (TDDFT) or Tamm-Dancoff approximation (DFT-TDA), have the wrong dimensionality for conical intersections between the ground state (S0) and the first excited state (S1) of the same multiplicity. This leads to unphysical state crossings. Here, we implement and assess the configuration-interaction-corrected Tamm-Dancoff approximation (CIC-TDA) that restores the correct dimensionality of conical intersections by including the coupling between the reference state and the intersecting excited state. We apply the CIC-TDA method to the S1/S0 conical intersections in ammonia (NH3), ethylene (C2H4), bithiophene (C8H6S2), azobenzene (C12H10N2), and 11-cis retinal protonated Schiff base (PSB11) in vacuo. We show that this black-box approach can produce potential energy surfaces (PESs) of comparable accuracy to multireference wave function methods. The method validated here can allow cost-efficient explorations of photoinduced electronically nonadiabatic dynamics, especially for large molecules and complex systems.

中文翻译：

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通过构型交互校正的 Tamm-Dancoff 方法研究的圆锥交点


圆锥形交点直接介导各种化学和生物系统中光诱导过程中的内能转换。由于布里渊定理，许多传统的电子结构方法，包括与 Hartree-Fock 参考的单个激励的构型交互，以及线性响应近似 （TDDFT） 或 Tamm-Dancoff 近似 （DFT-TDA） 中的瞬态密度泛函理论，对于相同多重性的基态 （S0） 和第一激发态 （S1） 之间的圆锥交点具有错误的维度。这会导致非物理状态交叉。在这里，我们实现并评估了配置-交互校正的 Tamm-Dancoff 近似 （CIC-TDA），它通过包括参考状态和相交激发态之间的耦合来恢复圆锥交点的正确维数。我们将 CIC-TDA 方法应用于真空中氨 （NH3 ）、乙烯 （C2H4）、联噻吩 （C8H6S2）、偶氮苯 （C12H10N2） 和 11-顺式视黄质子化希夫碱 （PSB11） 中的 S1/S0 锥形交点。我们表明，这种黑盒方法可以产生与多参考波函数方法相当精度的势能面 （PES）。此处验证的方法可以经济高效地探索光诱导电子非绝热动力学，特别是对于大分子和复杂系统。