Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

Ab initio cluster calculations of silica surface sites.

Authors
Murashov-V
Source
J Mol Struct 2003 May; 650(1-3):141-157
NIOSHTIC No.
20023448
Abstract
Silica surface sites, which can be formed in cleavage processes, and their hydrolyzed counterparts are investigated with ab initio cluster calculations. Natural Bond Orbital (NBO) theory is used to characterize bonding around silica surface sites. Higher energy lone pairs of electrons on oxygen atoms either hyperconjugate to vicinal silanol/siloxane antibonding orbitals or backdonate electron density via donor-acceptor pi-type bonding with participation of pd or p hybrids on silicon atoms. Upon substitution of hydroxyl groups of orthosilicic acid with silica monomers the strength of siloxane and silanol Si-O bonding increases as energies of bonding orbitals and contributions from p-orbitals decrease. Silanone sites and a complementary pair of silyl/siloxy radical sites are found to be the most stable geminal and single non-hydrolyzed sites, respectively. Atomic charges based on natural wavefunctions and on fitting to electrostatic potential, and characteristic bands of IR spectra associated with siloxane and silanol stretching vibrations of silica surface sites are reported.
Keywords
Silica-dusts; Silicates; Silicon-compounds; Chemical-properties; Chemical-reactions; Dust-particles; Dusts; Silicosis; Lung-disease; Surfactants; Aluminum-compounds
Contact
Vladimir Murashov, National Institute for Occupational Safety and Health, 1095 Willowdale Road, Morgantown, WV 26505, USA
CODEN
JMOSB4
CAS No.
7631-86-9; 14808-60-7
Publication Date
20030513
Document Type
Journal Article
Email Address
vmurashov@cdc.gov
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Issue of Publication
1-3
ISSN
0022-2860
NIOSH Division
HELD
Source Name
Journal of Molecular Structure
State
WV
TOP