[ital Ab] [ital initio] studies of cyclic water clusters (H[sub 2]O)[sub [ital n]], [ital n]=1--6. III. Comparison of density functional with MP2 results

Journal Article · Wed Mar 15 04:00:00 EST 1995 · Journal of Chemical Physics; (United States)

DOI:https://doi.org/10.1063/1.469499· OSTI ID:6401820

Xantheas, S S ^[1]

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1. Theory, Modeling and Simulation, Environmental Molecular Sciences Laboratory, Pacific Northwest Laboratory, Richland, Washington, 99352 (United States)

The optimal structures and harmonic vibrational frequencies of ring water clusters (H[sub 2]O)[sub [ital n]], [ital n]=1--6 are computed using density functional theory (DFT). The exchange functionals of Slater (S), Becke (B), the correlation functionals of Lee--Yang--Parr (LYP), Vosko--Wilk--Nusair (VWN), Perdew's local (PL), and gradient-corrected (P86) as well as their combinations are used to perform benchmark calculations on the water monomer and dimer. We use the augmented correlation-consistent polarized valence orbital basis set of double (aug-cc-pVDZ) and triple zeta quality (aug-cc-pVTZ) in order to compare the DFT with earlier MP2 results [J. Chem. Phys. [bold 99], 8774 (1993); [bold 100], 7523 (1994)]. Better overall agreement with the MP2 and experimental results for the water monomer and dimer is observed for the B--LYP and B--P86 functional combinations. The optimal structures, harmonic vibrational frequencies, and energetics of the clusters trimer through hexamer are computed at the B--LYP/aug-cc-pVDZ level of theory. This functional combination yields structures, energetics, and trends with cluster size that are in good agreement with the corresponding MP2 results.

• DOE Contract Number: AC06-76RL01830
• OSTI ID: 6401820
• Journal Information: Journal of Chemical Physics; (United States), Journal Name: Journal of Chemical Physics; (United States) Vol. 102:11; ISSN JCPSA6; ISSN 0021-9606
• Country of Publication: United States
• Language: English

Related Subjects

664500* -- Special Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
COMPARATIVE EVALUATIONS
CORRELATION FUNCTIONS
DIMERS
ELECTRONIC EQUIPMENT
EQUIPMENT
EVALUATION
FUNCTIONS
HARMONIC OSCILLATORS
HYDROGEN COMPOUNDS
MOLECULES
OPTIMIZATION
OSCILLATORS
OXYGEN COMPOUNDS
PERTURBATION THEORY
STRUCTURE FACTORS
WATER