0000000000427322
AUTHOR
Dean Antic
Calculation of the conformational dependence of valence and Rydberg states in n-tetrasilane
Abstract Previous CIS/6-31G ∗∗ and CASSCF/6-31G ∗ calculations of valence excited states of n -tetrasilane accounted qualitatively for the observed conformational dependence of condensed-phase UV absorption spectra. In an attempt to understand this result, we have performed CIS calculations with a larger basis set (MC-311G(2d) on Si, 6-311G on H, and 2s, 2p, and 2d diffuse orbitals at molecular center of mass). The first two excited states are of valence character at all dihedral angles if the molecule is isolated. When it is embedded in a rare gas cluster, the lowest four states are of valence character, and the results are nearly identical with those obtained without diffuse orbitals in t…
Rotational spectra of gauche perfluoro-n-butane, C4F10; perfluoro-iso-butane, (CF3)3CF; and tris(trifluoromethyl)methane, (CF3)3CH
Abstract The microwave spectra of the gauche conformer of perfluoro- n -butane, n -C 4 F 10 , of perfluoro- iso -butane, (CF 3 ) 3 CF, and of tris(trifluoromethyl)methane, (CF 3 ) 3 CH, have been observed and assigned. The rotational and centrifugal distortion constants for gauche n -C 4 F 10 are: A = 1058.11750(7) MHz, B = 617.6832(1) MHz, C = 552.18794(1) MHz, Δ J = 0.0257(5) kHz, δ J = 0.0052(3) kHz. A C–C–C–C dihedral angle, ω , of ∼55° has been determined. These values agree well with those obtained from a coupled cluster (CCSD/cc-PVTZ) calculation. The rotational and centrifugal distortion constants for iso -C 4 F 10 and iso -C 4 HF 9 are: B o = 816.4519(4) MHz, D J = 0.023(2) …