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Title: Relativistic coupled-cluster calculations on XeF{sub 6}: Delicate interplay between electron-correlation and basis-set effects

A systematic relativistic coupled-cluster study is reported on the harmonic vibrational frequencies of the O{sub h}, C{sub 3v}, and C{sub 2v} conformers of XeF{sub 6}, with scalar-relativistic effects efficiently treated using the spin-free exact two-component theory in its one-electron variant (SFX2C-1e). Atomic natural orbital type basis sets recontracted for the SFX2C-1e scheme have been shown to provide rapid basis-set convergence for the vibrational frequencies. SFX2C-1e as well as complementary pseudopotential based computations consistently predicts that both O{sub h} and C{sub 3v} structures are local minima on the potential energy surface, while the C{sub 2v} structure is a transition state. Qualitative disagreement between the present results for the O{sub h} structure and those from CCSD(T)-F12b calculations [Peterson et al., J. Phys. Chem. A 116, 9777 (2012)], which yielded a triply degenerate imaginary frequency for the O{sub h} structure, is attributed here to the high sensitivity of the computed harmonic frequencies of the t{sub 1u} bending modes to the basis-set effects of triples contributions.
Authors:
;  [1] ;  [2]
  1. Department of Chemistry, Institute for Theoretical Chemistry, The University of Texas at Austin, Austin, Texas 78712 (United States)
  2. Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz (Germany)
Publication Date:
OSTI Identifier:
22415972
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Chemical Physics; Journal Volume: 142; Journal Issue: 22; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CALCULATION METHODS; CONVERGENCE; ELECTRON CORRELATION; ELECTRONS; POTENTIAL ENERGY; POTENTIALS; RELATIVISTIC RANGE; SENSITIVITY; SPIN; SURFACES; XENON FLUORIDES; YIELDS