应用ABEEM/MM力场探究Na^+与氮-甲基乙酰胺及水的相互作用

Study on the Interactions Between Na^+ and N-Methylacetamide and Water by the ABEEM/MM

应用量子化学方法 MP2/6-311++G(d,p)//B3LYP/6-31+G(d,p)和原子-键电负性均衡浮动电荷分子力场(ABEEM/MM),对[Na(H_2O)n]+(n=3～8),[Na(NMA)n]+(n=3～8)和[Na(NMA)n(H_2O)m]+(n+m=4,6)(NMA=氮-甲基乙酰胺)体系的结构、结合能和电荷分布进行研究.在计算结果的基础上,构建上述体系的ABEEM/MM可极化势能函数,优选并确定相关参数.结果表明,ABEEM/MM的计算结果与量子化学的计算结果相符:Na+与配体间距离的平均绝对偏差(AAD)小于0. 007 nm,相对均方根偏差(RRMSD)小于3. 5%,夹角的AAD小于2. 4°,RRMSD小于2. 0%,结合能的AAD小于8. 9 k J/mol,RRMSD小于12. 4%;ABEEM/MM电荷分布与量子力学(QM)电荷分布的线性相关系数在0. 97以上.

The geometries,binding energies of[Na(H 2O)n]+(n=3-8),[Na(NMA)n]+(n=3-8),[Na(NMA)n(H 2O)m]+(n+m=4,6)(NMA=N-methylacetamide)were studied with the quantum chemical MP2/6-311++G(d,p)//B3LYP/6-31+G(d,p)level of theory and atom-bond electronegativity equalization method fused into molecular mechanics(ABEEM/MM)fluctuating charge force field.Based on the quantum chemical results,the polarizable ABEEM/MM potential energy functions of the above system were constructed,and the relative parameters were optimized and determined.The results show that the structures,binding energies,charge distributions obtained by ABEEM/MM are in good agreement with those from quantum chemical method(QM).The average absolute deviations(AAD)of distances of Na+-ligand,angles,and binding energies are less than 0.007 nm,2.4°,8.9 kJ/mol,respectively.The relative root mean square deviations(RRMSD)of distances of Na+-ligand,angles,and binding energies are less than 3.5%,2.0%,12.4%,respectively.The linear correlation coefficients of the charge distributions from ABEEM/MM and QM are above 0.97.