Full variational molecular orbital method: Application to the positron-molecule complexes
Full variational molecular orbital method: Application to the positron-molecule complexes
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DOI：
10.1002/(sici)1097-461x(1998)70:3
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发表时间：
1998-10-05
影响因子：
2.2
通讯作者：
Iguchi, K
中科院分区：
文献类型：
--
作者：
Tachikawa, M;Mori, K;Iguchi, K
采用分子轨道全变分方法，提出了正电子-分子络合物中正电子和电子的最佳高斯型轨道基组。导出了正电子和电子GTO参数如轨道指数、轨道中心和原子轨道线性组合系数的能量梯度的解析表达式。由FVMO方法得到的波函数显式地包含了电子或正电子轨道驰豫的影响，并且完全满足维里定理和Hellmann-Feynman定理。我们证明了在不同的正电子-原子和阴离子体系中每个轨道指数的最佳化，并估计了正电子亲和力(PA)作为它们之间的能量差。我们在小基组下得到的PA与Hartree-Fock的数值结果符合得很好。用FVMO方法计算了正电子-分子体系中的OH-和[OH-；e(+)]物种。这一结果表明，正电子基组不仅变得更加弥散，而且还向氧原子移动。此外，我们还应用这种方法同时测定了LiH和LiD分子的核波函数和电子波函数，并直接得到了同位素效应。(C)1998年John Wiley&Sons，Inc.
Optimal Gaussian-type orbital (GTO) basis sets of positron and electron in positron-molecule complexes are proposed by using the full variational treatment of molecular orbital (FVMO) method. The analytical expression for the energy gradient with respect to parameters of positronic and electronic GTO such as the orbital exponents, the orbital centers, and the Linear combination of atomic orbital (LCAO) coefficients, is derived. Wave functions obtained by the FVMO method include the effect of electronic or positronic orbital relaxation explicitly and satisfy the virial and Hellmann-Feynman theorems completely. We have demonstrated the optimization of each orbital exponent in various positron-atomic and anion systems, and estimated the positron affinity (PA) as the difference between their energies. Our PA obtained with small basis set is in good agreement with the numerical Hartree-Fock result. We have calculated the OH- and [OH-; e(+)] species as the positron-molecular system by the FVMO method. This result shows that the positronic basis set not only becomes more diffuse but also moves toward the oxygen atom. Moreover, we have applied this method to determine both the nuclear and electronic wave functions of LiH and LiD molecules simultaneously, and obtained the isotopic effect directly. (C) 1998 John Wiley & Sons, Inc.