密度泛函计算中基组的收敛现象:强成键体系CO分子

Basis Set Convergence Phenomenon in Density Functional Theory: CO as an Example of Strongly Bonded Systems

探讨了用密度泛函理论中7个常见交换-相关密度泛函及8种常见Dunning调和相关基组处理CO分子的三种性质(平衡键长、谐振基频和离解能)时表现出的基组收敛现象.用Dunning的单指数插补法,求得了上述性质的全基组极限值.用扩展的调和相关基组,发现键长的系统误差在0.002 9(LDA)到0.007 3(BP86)之间,基频误差为17(LDA)至56(B3BP86)cm-1,离解能误差为12.6(BLYP)至186.6(LDA)kJ/mol.这些结果对系统地认识波函数的基组收敛现象将提供有益启示.

In this work we systematically investigate the basis set convergence phenomenon with seven commonly used approximate exchange-correlation energy density functionals and eight Dunning correlated basis sets for three physicochemical properties,equilibrium bond distance,first harmonic frequency,and dissociation energy,of the CO molecule.By employing Dunning＇s single-exponent extrapolation approach,we have obtained the complete basis set limit for these properties.With the augmented correlation basis sets employed in this study,we found that the systematic error in the equilibrium bond distance is between 0.002 9（LDA） to 0.007 3 （BP86）,that in the first harmonic frequency lies between 17（LDA） and 56（B3BP86） cm-1,and that in the dissociation energy falls between 12.6（BLYP） and 186.6 kJ/mol.These results shed lights on our systematic understanding of the basis set convergence phenomenon in the wave function.