Parallelization of MRCI based on hole-particle symmetry

The parallel implementation of multireference configuration interaction program based on the hole-particle symmetry is described. The platform to implement the parallelization is an Intel-Architectural cluster consisting of 12 nodes, each of which is equipped with two 2.4-G XEON processors, 3-GB memory, and 36-GB disk, and are connected by a Gigabit Ethernet Switch. The dependence of speedup on molecular symmetries and task granularities is discussed. Test calculations show that the scaling with the number of nodes is about 1.9 (for C1 and Cs), 1.65 (for C2v), and 1.55 (for D2h) when the number of nodes is doubled. The largest calculation performed on this cluster involves 5.6 x 10(8) CSFs.     

Involvement of excited triplet state in the photodissociation of cyclobutane

The potential energy curves (PECs) of the ground state and the low‐lying excited states for the photodissociation of cyclobutane have been calculated at the multi‐reference configuration interaction with singlet and doublet excitation (MRCISD) and the multi‐reference second order perturbation theory (MRPT2). Firstly, the PECs are constructed following a reaction path determined by semiclassical dynamics simulation, which suggests that the lowest triplet state of tetramethylene is involved in the photodissociation of cyclobutane. Then, the adiabatic PECs are calculated for the breaking processes of C1? C3 and C2? C4 bond respectively. The singlet‐triplet PECs' intersections have been found in the two breaking C? C bond processes. During the breaking process of the second C2? C4 bond, a local minimum has been found on the PEC of the lowest triplet state, which gives us some insight to reinterpret the experimental observed diradical intermediate as being trapped in its triplet state. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2008     

S2O分子的局域势能面和振动光谱的解析

用MRCISD和MRPT2计算了S2O分子的局域势能面，对计算点完成了力场多项式拟合和振动组态相互作用的计算.然后，对其基态(1A′)和激发态(1A′)的振动模式和振动光谱进行分析.通过调节力常数，势能面得到进一步改进.与已有的实验能谱数据进行比较，基态与激发态的均方差分别为3852cm-1和644cm-1. 关键词： S2O 势能面 能谱 MRCISD MRPT2     

Be和B的几个小分子及其离子的电子结构

B和Be化合物的电子结构研究可以为~(10)Be质谱检测中~(10)B干扰的消除提供 理论依据。用B3LYP/6-311 + + G（3df, 3pd）方法和G3方法计算了BF(~1∑~+)， BeF~(~2∑~+)，HBO(~1A')，HBeO(~2∑~+)，HBeF(~1∑~+)，BBeB(~1A_1)，H_2BO (~2B_2)和H_3BO(~1A')等分子及其负离子BF~- (~2∏)，BeF~- (~1∑~+)，HBO~- (~2A')，HBeO~- (~1∑~+)，HBeF~- (~2A')，BBeB~- (~2A_1)，H_2BO~- (~1A_1) ，H_3BO~-(~2A')的电子结构，并利用CASSCF-MRCISD方法计算了BeF(2~∑~+) /BeF~-(~1∑~+)，BF(~1∑~+)/BF~-(~2∏)和BF(~3∏)/BF~-(~4∑~-)的热能曲线。 探讨了这些体系的稳定性。解释了~(10)Be质变测量方法中的有关结果。     

MRCISD程序的改进

报道了一个改进的多参考态组态相互作用计算程序,通过对照计算比较了该程序与Gaussian-94W和Gaussian-98W中CISD的效率,并在微机上实现了组态数超过10^7的大规模CI计算。此外,为了使CI计算能够应用于更大的体系,还报道了一些近似CI方法的计算结果。