Department of Physics, University of Oulu, P.O. Box 3000, FI-90014 Oulu, Finland.
J Phys Chem A. 2011 Sep 29;115(38):10617-23. doi: 10.1021/jp2052739. Epub 2011 Sep 8.
Ab initio values of the absolute shielding constants of phosphorus and hydrogen in PH(3) were determined, and their accuracy is discussed. In particular, we analyzed the relativistic corrections to nuclear magnetic resonance (NMR) shielding constants, comparing the constants computed using the four-component Dirac-Hartree-Fock approach, the four-component density functional theory (DFT), and the Breit-Pauli perturbation theory (BPPT) with nonrelativistic Hartree-Fock or DFT reference functions. For the equilibrium geometry, we obtained σ(P) = 624.309 ppm and σ(H) = 29.761 ppm. Resonance frequencies of both nuclei were measured in gas-phase NMR experiments, and the results were extrapolated to zero density to provide the frequency ratio for an isolated PH(3) molecule. This ratio, together with the computed shielding constants, was used to determine a new value of the nuclear magnetic dipole moment of (31)P: μ(P) = 1.1309246(50) μ(N).
我们确定了 PH(3)中磷和氢的绝对屏蔽常数的从头算值，并讨论了其准确性。特别是，我们分析了核磁共振（NMR）屏蔽常数的相对论修正，比较了使用四分量狄拉克-哈特ree-fock 方法、四分量密度泛函理论（DFT）和 Breit-Pauli 微扰理论（BPPT）计算的常数与非相对论 Hartree-Fock 或 DFT 参考函数。对于平衡几何，我们得到 σ(P) = 624.309 ppm 和 σ(H) = 29.761 ppm。我们在气相 NMR 实验中测量了两个核的共振频率，并将结果外推至零密度，以提供孤立 PH(3)分子的频率比。该比值与计算出的屏蔽常数一起用于确定 (31)P 的核磁矩的新值：μ(P) = 1.1309246(50) μ(N)。
