ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
Several structures of beryllium borohydride (BeB2H8) have been studied with techniques based on many-body perturbation theory (MBPT). Energies calculated at the MBPT(4) level with a basis set of 85 contracted Gaussian functions support the two structure hypothesis of Nibler, although a qualitative MBPT(4) asymmetric stretching potential indicates that the C3v double-minimum structure is unstable with respect to a more highly symmetric D3d model with two sets of equivalent triple hydrogen bridges. The theoretical free energy difference between the D3d structure and a diborane-like model having D2d symmetry is 1.1 kcal/mol, with the latter predicted to be more stable. Uncertainties in the theoretical force field and those resulting from the finite nature of the basis set, however, may change this value by several kcal/mol. Principal evidence for the two-structure proposal comes from MBPT(2) harmonic frequencies and infrared absorption intensities, which are found to be consistent with the published vibrational spectra. These are used in a tentative assignment of most of the observed features. Unfortunately, the experimentally observed dipole moment of 2.06 D cannot be explained at present.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.454532
