强磁场下基于Hylleraas-Gaussian基的双电子双原子分子的谱结构

Recently, the third molecular bonding mechanism besides the covalent bond and the ionic bond, i.e., the perpendicular paramagnetic bonding, is found through the investigation on the hydrogen molecule in non-parallel magnetic fields with the wave function constructed by the isotropic Gaussian basis set. However, the isotropic Gaussian basis can not reflect very well the anisotropy of the electron in the non-aligned magnetic field, since the external magnetic field results in the lowered symmetry of the electron of the atomic and molecular systems. The anisotropic Gaussian basis function can reflect this character very well. The anisotropic Hylleraas-Gaussian basis function is much better for the two-electron atomic or molecular systems because the correlation of the electrons is contained directly in this kind of function. Therefore, in this project, the anisotropic Hylleraas−Gaussian basis function is employed to calculate the hydrogen molecule in non-parallel magnetic fields. The accurate spectral structure of the singlet and triplet state with gerade and ungerade parity will be obtained in order for the deep investigation on the the relationship between the the perpendicular paramagnetic bonding and the magnetic field. We plan to extend this theory and methods for the hydrogen molecule to the other homonuclear molecules and heteronuclear molecules which also have two electrons, compare the electronic behavior of these molecules in magnetic fields, make it clear that whether this new bonding mechanism is valid for the other two-electron molecules or not, and finally obtain the the general patterns of the two-electron diatomic molecules in stong magnetic fields.

最近，基于各项同性Gaussian基对非平行磁场下氢分子展开的研究使人们发现了共价键和离子键之外的第三种分子成键机制，即垂直顺磁成键。由于外磁场的存在使得原子分子内电子的对称性下降，各项同性Gaussian基不能很好地反映电子在非平行磁场下的各向异性特点，而各向异性Gaussian基则能较好地描述电子的这一特点，考虑了电子关联的各向异性Hylleraas-Gaussian基在处理双电子原子或分子时则具有更大的优势。因此，本项目拟采用各向异性Hylleraas-Gaussian基计算非平行磁场下的氢分子，取得最低单三重奇偶态比较准确的谱结构，进一步挖掘垂直顺磁成键机制与磁场之间的关系，并将计算氢分子的理论和方法推广至其他拥有两个电子的同核分子和异核分子，比较这些分子在磁场下的电子行为，明确这种新的成键机制是否适用于其他双电子双原子分子，最终阐明双电子双原子分子在强磁场下的普遍规律。

本项目系统的研究了外磁场下的单电子和双电子分子体系，取得了一定进展：（1）对于非平行场下H2+，利用携带规范相因子的各项异性高斯原子轨道线性叠加形成分子轨道，进而构建波函数，得到了1u态更为精确的数据；（2）对于平行磁场下HeH+，通过独立电子模型和泡利不相容原理，运用各项异性高斯原子轨道构建波函数，取得了最低单态和三重态较为精确的能量和平衡距离以及势能曲线。特别是，现有计算表明，最低三重态的解离能随磁场的增强而单调增大。