Jm. Galbraith et al., THE VIBRATIONAL FREQUENCIES OF BORANE (BH3) - A COMPARISON OF HIGH-LEVEL THEORETICAL RESULTS, Journal of molecular structure, 300, 1993, pp. 281-288
Using the borane molecule, BH3, as an example, a detailed comparison i
s made among the results achieved using many levels of theory for the
treatment of electron correlation. In particular, with three different
basis sets ranging from a simple double-zeta plus polarization (DZP)
to the very flexible triple-zeta plus two sets of polarization functio
ns plus higher angular momentum functions (TZ2P(fd)), total energetic,
geometrical and harmonic vibrational frequency results from several o
f the more complete single reference methods of electron correlation a
re compared to the full configuration interaction (FCI) results. Empha
sis is placed on comparison of augmented coupled cluster (CCSD(T)) the
ory and the CI method including all singles, doubles, triples and quad
ruples (CISDTQ) methods with FCI. These high-level results may also pr
ovide some additional insight into the ongoing controversy surrounding
the experimentally assigned fundamental vibrational frequencies of BH
3. The TZ2P(f,d) CCSD(T) harmonic vibrational frequencies predicted in
this work were omega1 = 2567, omega2 = 1163, omega3 = 2696 and omega4
= 1223 cm-1 implying experimental misassignments by Kaldor and Porter
[J. Am. Chem. Soc., 93 (1971) 2140] of the third and fourth vibration
al frequencies, in agreement with previous theoretical works.