Kumar Anupriya, Kołaski Maciej, Kim Kwang S
Department of Chemistry, Pohang University of Science and Technology, San 31, Hyojadong, Namgu, Pohang 790-784, Korea.
J Chem Phys. 2008 Jan 21;128(3):034304. doi: 10.1063/1.2822276.
Structures of the ground state pyrrole-(H2O)n clusters are investigated using ab initio calculations. The charge-transfer driven femtosecond scale dynamics are studied with excited state ab initio molecular dynamics simulations employing the complete-active-space self-consistent-field method for pyrrole-(H2O)n clusters. Upon the excitation of these clusters, the charge density is located over the farthest water molecule which is repelled by the depleted pi-electron cloud of pyrrole ring, resulting in a highly polarized complex. For pyrrole-(H2O), the charge transfer is maximized (up to 0.34 a.u.) around approximately 100 fs and then oscillates. For pyrrole-(H2O)2, the initial charge transfer occurs through the space between the pyrrole and the pi H-bonded water molecule and then the charge transfer takes place from this water molecule to the sigma H-bonded water molecule. The total charge transfer from the pyrrole to the water molecules is maximized (up to 0.53 a.u.) around approximately 100 fs.
使用从头算计算研究了基态吡咯 - (H₂O)ₙ 团簇的结构。利用激发态从头算分子动力学模拟，采用完全活性空间自洽场方法对吡咯 - (H₂O)ₙ 团簇进行研究，探讨了电荷转移驱动的飞秒尺度动力学。这些团簇被激发时，电荷密度位于距离最远的水分子上，该水分子被吡咯环耗尽的π电子云排斥，从而形成高度极化的复合物。对于吡咯 - (H₂O)，电荷转移在大约100飞秒时达到最大值（高达0.34原子单位），然后振荡。对于吡咯 - (H₂O)₂，初始电荷转移通过吡咯与π氢键合水分子之间的空间发生，然后电荷从该水分子转移到σ氢键合水分子。从吡咯到水分子的总电荷转移在大约100飞秒时达到最大值（高达0.53原子单位）。
