Time-dependent wave packet study on trans-cis isomerization of HONO.
Time-dependent wave packet study on trans-cis isomerization of HONO.
复制标题
HONO 反式顺式异构化的时间依赖性波包研究。
作者：
F. Richter;P. Rosmus;F. Gatti;H. Meyer
采用全六维从头算势能面和核运动哈密顿量，对HONO的顺反异构化反应进行了含时计算。采用多组态含时Hartree方法传播六维波包。初始激励被选择为局部拉伸模式和HON局部弯曲模式的激励。分析了两种异构体中OH伸缩模能量区域内2 ~ 5 ps内的能量再分配。傅里叶变换后的频域谱是由先前用时间无关变分法计算的本征态所得到的。结果还比较了经典的轨迹计算Thomson等人。经验表面。与基质实验一致，发现顺式->反式异构化比相反的相互转化快得多。分子内动力学过程非常复杂，涉及大量的弱激发离域本征态和非简谐共振。特别是在顺式异构体中，HON弯曲局域模的激发导致顺反离域模中的快速能量重新分布。无论是在顺式或反式的OH伸缩本地模式的激发产生快速异构化，在一致的强本地化字符的相应的本征态变分计算Richter等。和HONO的气相光谱。
Using a full six-dimensional ab initio potential energy surface and nuclear motion Hamiltonian, time-dependent computations were performed for the cis-trans isomerization of HONO. The multiconfiguration time-dependent Hartree method was used to propagate the six-dimensional wave packets. The initial excitations were chosen to be excitations of the local stretch modes and the HON local bend mode. The energy redistribution within 2 to 5 ps in the energy region of the OH stretching modes in both isomers was analyzed. The Fourier transformed frequency domain spectra were attributed to the eigenstates calculated previously by the time-independent variational approach. The results are also compared with classical trajectory computations of Thomson et al. on empirical surfaces. In agreement with matrix experiments, the cis-->trans isomerization was found to be much faster than the opposite interconversion. The intramolecular dynamics were found to be very complex involving numerous weakly excited delocalized eigenstates and anharmonic resonances. Particularly in the cis-isomer, the excitation of the HON bending local mode leads to fast energy redistribution in cis-trans delocalized modes. Neither the excitation of the OH stretching local mode in the cis nor in the trans form produces a fast isomerization, in agreement with the strongly localized characters of the corresponding eigenstates calculated variationally by Richter et al. and the gas phase spectra of HONO.