Hanni Matti, Lantto Perttu, Runeberg Nino, Jokisaari Jukka, Vaara Juha
NMR Research Group, Department of Physical Sciences, P.O. Box 3000, FIN-90014 University of Oulu, Finland.
J Chem Phys. 2004 Sep 22;121(12):5908-19. doi: 10.1063/1.1785146.
Quantum chemical calculations of the nuclear shielding tensor, the nuclear quadrupole coupling tensor, and the spin-rotation tensor are reported for the Xe dimer using ab initio quantum chemical methods. The binary chemical shift delta, the anisotropy of the shielding tensor Delta sigma, the nuclear quadrupole coupling tensor component along the internuclear axis chi( parallel ), and the spin-rotation constant C( perpendicular ) are presented as a function of internuclear distance. The basis set superposition error is approximately corrected for by using the counterpoise correction (CP) method. Electron correlation effects are systematically studied via the Hartree-Fock, complete active space self-consistent field, second-order Møller-Plesset many-body perturbation, and coupled-cluster singles and doubles (CCSD) theories, the last one without and with noniterative triples, at the nonrelativistic all-electron level. We also report a high-quality theoretical interatomic potential for the Xe dimer, gained using the relativistic effective potential/core polarization potential scheme. These calculations used valence basis set of cc-pVQZ quality supplemented with a set of midbond functions. The second virial coefficient of Xe nuclear shielding, which is probably the experimentally best-characterized intermolecular interaction effect in nuclear magnetic resonance spectroscopy, is computed as a function of temperature, and compared to experiment and earlier theoretical results. The best results for the second virial coefficient, obtained using the CCSD(CP) binary chemical shift curve and either our best theoretical potential or the empirical potentials from the literature, are in good agreement with experiment. Zero-point vibrational corrections of delta, Delta sigma, chi (parallel), and C (perpendicular) in the nu=0, J=0 rovibrational ground state of the xenon dimer are also reported.
使用从头算量子化学方法，报道了对氙二聚体的核屏蔽张量、核四极耦合张量和自旋-旋转张量的量子化学计算。给出了二元化学位移δ、屏蔽张量的各向异性Δσ、沿核间轴的核四极耦合张量分量χ(∥)以及自旋-旋转常数C(⊥)随核间距的变化函数。通过使用抗衡校正(CP)方法对基组叠加误差进行了近似校正。在非相对论全电子水平上，通过哈特里-福克、完全活性空间自洽场、二阶莫勒-普列斯特定理多体微扰以及耦合簇单双激发(CCSD)理论系统地研究了电子相关效应，最后一种理论包括有无非迭代三激发。我们还报道了使用相对论有效势/核心极化势方案获得的高质量氙二聚体理论原子间势。这些计算使用了cc-pVQZ质量的价基组，并补充了一组键中函数。计算了氙核屏蔽的第二维里系数，它可能是核磁共振光谱中实验表征最好的分子间相互作用效应，并将其作为温度的函数进行计算，与实验和早期理论结果进行了比较。使用CCSD(CP)二元化学位移曲线以及我们最好的理论势或文献中的经验势获得的第二维里系数的最佳结果与实验结果吻合良好。还报道了氙二聚体在ν=0、J=0振转基态下δ、Δσ、χ(∥)和C(⊥)的零点振动校正。
