用RI-MP2、RIJCOSX-MP2方法计算分子间相互作用能

The Calculations of Intermolecular Interaction Energy Using the RI-MP2 and RIJCOSX-MP2 Methods

研究RI-MP2、RIJCOSX-MP2 2种快速MP2方法用于分子间相互作用能计算时的大小一致性和基函数重叠误差(BSSE)的均衡校正问题。选择H2O…H2O、CH4…CH4、CH4…C6H6、C6H6…C6H6和Guanine…Cytosine 5个典型体系,在Def2-TZVPPD基函数水平下进行计算,结果表明这两种快速MP2方法满足大小一致性,CP(Counter Poise,method)均衡校正法进行BSSE校正时,与传统MP2相比较,RI-MP2最大相对误差仅有0.6%,RIJCOSX-MP2达10.3%。说明RI-MP2方法的BSSE可以用CP方法校正,RIJCOSX-MP2用CP校正BSSE应慎重。

It was investigated that the size consistency and basis set superposition error（BSSE） are corrected by the two fast methods containing RI-MP2 and RIJCOSX-MP2 with the calculation of the intermolereular interaction energy. Five typical systems including HE O… H2O, CH4… CH4, CH4… C6H6, C6H6… C6H6 and Guanine… Cytosine were calculated based on the level of Def2-TZVPPD. The results show that the two fast MP2 methods were content with the size consistency. The biggest relative error of RI-MP2 was only 0. 6 % and the biggest relative error of RIJ- COSX-MP2 was 10. 3 % when the BSSE was corrected by CP method. Comparing with the traditional MP2,it is indicated that the BBSE of RI-MP2 could be corrected by CP method, however,it should be prudent that correct the BSSE of RIJCOSX-MP2 bv CP method.