Lynch Benjamin J, Zhao Yan, Truhlar Donald G
Department of Chemistry and Supercomputer Institute, University of Minnesota, Minneapolis, Minnesota 55455-0431, USA.
J Phys Chem A. 2005 Mar 3;109(8):1643-9. doi: 10.1021/jp045847m.
Three new multicoefficient correlation methods (MCCMs) called BMC-QCISD, BMC-CCSD, and BMC-CCSD-C are optimized against 274 data that include atomization energies, electron affinities, ionization potentials, and reaction barrier heights. A new basis set called 6-31B(d) is developed and used as part of the new methods. BMC-QCISD has mean unsigned errors in calculating atomization energies per bond and barrier heights of 0.49 and 0.80 kcal/mol, respectively. BMC-CCSD has mean unsigned errors of 0.42 and 0.71 kcal/mol for the same two quantities. BMC-CCSD-C is an equally effective variant of BMC-CCSD that employs Cartesian rather than spherical harmonic basis sets. The mean unsigned error of BMC-CCSD or BMC-CCSD-C for atomization energies, barrier heights, ionization potentials, and electron affinities is 22% lower than G3SX(MP2) at an order of magnitude less cost for gradients for molecules with 9-13 atoms, and it scales better (N6 vs N,7 where N is the number of atoms) when the size of the molecule is increased.
三种新的多系数相关方法（MCCMs），即BMC-QCISD、BMC-CCSD和BMC-CCSD-C，针对包括原子化能、电子亲和能、电离势和反应势垒高度在内的274个数据进行了优化。一种名为6-31B(d)的新基组被开发出来，并用作新方法的一部分。BMC-QCISD在计算每个键的原子化能和势垒高度时，平均绝对误差分别为0.49和0.80千卡/摩尔。对于相同的两个量，BMC-CCSD的平均绝对误差为0.42和0.71千卡/摩尔。BMC-CCSD-C是BMC-CCSD的一个同样有效的变体，它采用笛卡尔基组而非球谐基组。对于具有9至13个原子的分子，BMC-CCSD或BMC-CCSD-C在原子化能、势垒高度、电离势和电子亲和能方面的平均绝对误差比G3SX(MP2)低22%，且在计算梯度时成本低一个数量级，并且当分子尺寸增大时，其标度性更好（N6对N7，其中N是原子数）。
