Relativistic effects on molecules containing p-block elements

Abstract

Relativistic effects on molecules containing sixth-row and seventh-row p-block elements are evaluated with two-component methods using relativistic effective core potentials and effective one-electron spin-orbit operator : Spin-orbit and scalar relativistic effects on geometries, vibrational frequencies and energies for group 17 fluorides $EF_3$ (E=I, At and Element 117); Spin-orbit effects on the p-block element monohydrides MH(M=Tl~Rn and Element 113~118); Two-component relativistic calculations for the hetero diatomic molecules containing heavy p-block elements, TlAt and (113)(117). The inclusion of relativistic effects makes the $D_{3h}$ structure of (117)$F_3$ a stable local minimum, while $IF_3$ and $AtF_3$ retain $C_{2v}$ local minima even with relativistic effects. Spin-orbit interactions elongate the bond lengths and decrease the harmonic vibrational frequencies. Spin-orbit effects widen the bond angle of $C_{2v}$ structures of $IF_3$ and $AtF_3$, i.e., spin-orbit effects diminish the second-order Jahn-Teller term. In the case of $AtF_3$, spin-orbit interactions increase the bond lengths by 0.044 and 0.023 Å for $r_e^{eq}$ and $r_e^{ax}$, respectively. The bond angle increases by 3.9˚ due to spin-orbit interactions in addition to increase of 4.8˚ by other scalar relativistic effects. For (117)$F_3$, spin-orbit effects increase the bond length by 0.109 Å . The dissociation energy is increased due to spin-orbit interactions by 1.24 eV at the coupled cluster single and double with perturbated triples[CCSD(T)] level while the dissociation energies of $IF_3$ and $AtF_3$ are decreased. Spin-orbit effects on the bond lengths and dissociation energies of sixth- and seventh-row p-block element monohydrides MH(M=Tl~Rn and Element 113~118) are evaluated at the coupled-cluster level of theory. Spin-orbit effects play a dominant role in the determination of molecular properties for the seventh-row hydrides. Spin-orbit effects on the bond lengths and dissociation ...