Ab initio calculations of vibronic spectra and dynamics for small polyatomic molecules: The role of Duschinsky effect
多原子分子之電子光譜及其激發態動力學的第一 原理計算: 魯新斯基(Duschinsky)效應

A. M. Mebel, M. Hayashi, K. K. Liang, S. H. Lin
J. Phys. Chem. A 103, 10674 (1999)

The Duschinsky effect has been shown to be significant in spectroscopy and dynamics of molecules that involve the π-π* transitions. In this paper, we present a derivation of exact expressions for optical absorption and radiationless transitions in polyatomic molecules with displaced-distorted-rotated harmonic potential surfaces. In the formulation, we take into account the temperature effect exactly. The application of this new formulation is demonstrated for ethylene and allene, where the Duschinsky effect in the first singlet excited electronic state is very strong.

小分子(如乙烯)的 躍遷過程會改變激發態的構造。因此魯新斯基效應對於其電子光譜及其激發態的動力學起決定性之作用。在本文我們推導出一組描述多原子分子的吸收光譜及非輻射躍遷過程之完整方程式。其中魯新斯基效應(即激發態的勢能面相對於機態勢能面具有平移及彎曲變形的情況)均已詳細考慮。
我們將第一原理計算引進此理論並應用到乙烯和丙二烯分子。這些分子的第一激發態具有非常顯著之魯新斯機效應，我們成功地解釋了為何乙烯之吸收光譜顯示出已知分子中譜寬最寬之分子。我們也用第一原理計算算出乙烯的無輻射躍遷過程之數度為10皮秒。

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