ISSN:
1089-7690
Source:
AIP Digital Archive
Topics:
Physics
,
Chemistry and Pharmacology
Notes:
We studied the structure of disiloxane (H3Si–O–SiH3), silanol (H3Si–OH), and the silanol anion (H3Si–O−) with ab initio molecular orbital theory and the correlation consistent polarized basis sets of Dunning and co-workers. We present results for the correlation consistent polarized valence double zeta (cc-pVDZ), triple zeta (cc-pVTZ), and quadruple zeta [cc-pVQZ(-g)] basis sets. Optimized geometries and energies are given at both the restricted Hartree–Fock (RHF) level and with the inclusion of electron correlation by second order Møller–Plesset perturbation theory (MP2). The correlation consistent basis sets provide a systematic expansion of the orbital basis set, with each set of additional functions adding a similar contribution to the correlation energy. We find that the calculated molecular properties show exponential convergence with increasing basis set size. These calculations answer long-standing questions regarding the structure and barrier to linearization of disiloxane. Results at the highest level of theory [MP2/cc-pVQZ(-g)] for disiloxane gave a Si–O–Si bond angle of 147.0°, a Si–O bond length of 1.641 A(ring), and a barrier to linearization of 0.4 kcal/mol. All of these values are in excellent agreement with experimental results. Similar calculations for silanol gave a Si–O bond length of 1.655 A(ring), an O–H bond of 0.955 A(ring), and a Si–O–H angle of 117.9°. The MP2/cc-pVQZ(-g) deprotonation energy (ΔE0) for silanol, calculated as the energy difference between silanol and its anion, is −366.6 kcal/mol. The effects of electron correlation at the MP4 level are studied in all three molecules using the cc-pVDZ and cc-pVTZ basis sets. © 1995 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.470169
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