Self‐Consistent Molecular Orbital Methods. VI. Energy Optimized Gaussian Atomic Orbitals
Self‐Consistent Molecular Orbital Methods. VI. Energy Optimized Gaussian Atomic Orbitals
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自洽分子轨道方法 VI。
DOI：
10.1063/1.1672736
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发表时间：
1970
影响因子：
4.4
通讯作者：
J. Pople
中科院分区：
文献类型：
--
作者：
R. Ditchfield;W. Hehre;J. Pople
给出了氢和第一行原子硼到氟的最小基础原子轨道，表示为 N 高斯函数的和。展开系数和高斯指数是通过最小化原子基态的总计算能量来确定的。对于高达六个高斯的展开长度，报告了两组原子轨道。在我们描述为无约束的第一组中，2s 和 2p 原子轨道使用不同的高斯指数。在第二组中，2s 和 2p 原子轨道被限制为共享相同的高斯指数。结果表明，这一约束在分子计算中的计算速度方面产生了显着的增益，但不会严重降低给定 N 的原子轨道的质量。将此处提出的收缩集与先前对第一行原子的未收缩基组的研究进行比较，表明未收缩高斯指数与收缩函数的指数的近似值很差......
Minimal basis atomic orbitals expressed as sums of N Gaussian functions are presented for hydrogen and for the first row atoms boron to fluorine. The expansion coefficients and Gaussian exponents are determined by minimizing the total calculated energy of the atomic ground state. For expansion lengths of up to six Gaussians, two sets of atomic orbitals are reported. In the first set, which we describe as unconstrained, different Gaussian exponents are used for the 2s and 2p atomic orbitals. In the second set, the 2s and 2p atomic orbitals are constrained to share the same Gaussian exponents. It is shown that this constraint, which produces a significant gain in computational speed in molecular calculations, does not seriously reduce the quality of the atomic orbitals for given N. A comparison of the contracted sets presented here with previous studies on uncontracted basis sets for the first row atoms, shows that the uncontracted Gaussian exponents are a poor approximation to those of the contracted funct...