TY - JOUR
T1 - The onset of dissociation in the aqueous LiOH clusters
T2 - A solvation study with the effective fragment potential model and quantum mechanics methods
AU - Yoshikawa, Akihiko
AU - Morales, Jorge A.
N1 - Funding Information:
The authors would like to express their gratitude to Prof. Mark S. Gordon and Dr Mike Schmidt (Iowa State University) for their helping discussions on the EFP method and the gamess program. All the present calculations have been completed at the Texas Tech University High Performance Computer Center (TTU HPCC), to which generous use of computer time and technical support are gratefully acknowledged. This research was supported in part by the Robert A. Welch Foundation grant D-1539 and by an award from Research Corporation. Also, acknowledgment is made to the donors of The American Chemical Society Petroleum Research Fund for partial support of this research.
PY - 2004/7/26
Y1 - 2004/7/26
N2 - The first systematic study on the solvation of the LiOH(H 2O)n (n=1-6,8) clusters is herein presented by using both the molecular-mechanics effective fragment potential (EFP) model and full quantum mechanics methods. Aqueous clusters are sequentially calculated first with the LiOH solute molecule described by a restricted Hartree-Fock (RHF) wavefunction and the H2O solvent molecules by the EFP model (EFP/RHF), and then with the full quantum mechanics RHF and Møller-Pleset second-order perturbation (MP2) theories. Calculated properties include equilibrium geometries, Mulliken charges, bond lengths and orders, and relative energies inter alia. Present results indicate that at the least six H 2O molecules are necessary to be added to one LiOH molecule to cause its spontaneous dissociation into a Li+/OH- separated ion pair. Another instance of dissociation is also observed in one of the LiOH(H2O)8 isomers. EFP/RHF reasonably reproduces RHF structural properties and dissociation patterns but discrepancies arise in the solute charge description. Comparisons of the present theoretical results with previous EFP studies and with a few experimental data are also discussed.
AB - The first systematic study on the solvation of the LiOH(H 2O)n (n=1-6,8) clusters is herein presented by using both the molecular-mechanics effective fragment potential (EFP) model and full quantum mechanics methods. Aqueous clusters are sequentially calculated first with the LiOH solute molecule described by a restricted Hartree-Fock (RHF) wavefunction and the H2O solvent molecules by the EFP model (EFP/RHF), and then with the full quantum mechanics RHF and Møller-Pleset second-order perturbation (MP2) theories. Calculated properties include equilibrium geometries, Mulliken charges, bond lengths and orders, and relative energies inter alia. Present results indicate that at the least six H 2O molecules are necessary to be added to one LiOH molecule to cause its spontaneous dissociation into a Li+/OH- separated ion pair. Another instance of dissociation is also observed in one of the LiOH(H2O)8 isomers. EFP/RHF reasonably reproduces RHF structural properties and dissociation patterns but discrepancies arise in the solute charge description. Comparisons of the present theoretical results with previous EFP studies and with a few experimental data are also discussed.
KW - Charge transfer
KW - Effective fragment potential model
KW - Solvation effects
KW - Spontaneous dissociation of ionic compounds in aqueous clusters
UR - http://www.scopus.com/inward/record.url?scp=3543048024&partnerID=8YFLogxK
U2 - 10.1016/j.theochem.2004.04.047
DO - 10.1016/j.theochem.2004.04.047
M3 - Article
AN - SCOPUS:3543048024
SN - 0166-1280
VL - 681
SP - 27
EP - 40
JO - Journal of Molecular Structure: THEOCHEM
JF - Journal of Molecular Structure: THEOCHEM
IS - 1-3
ER -