120th General Meeting of the KCS

Type Poster Presentation
Area Physical Chemistry
Room No. Exhibition Hall 2+3
Time 10월 20일 (금요일) 13:00~14:30
Code PHYS.P-112
Subject Exponential Law for Complete Basis Limit of CCSD(T) Theory for OH Vibrational Potential Energies of Water Molecules
Authors Ki Young Jeon, Mino Yang*
Department of Chemistry, Chungbuk National University, Korea
Abstract Quantum chemical electronic energy of a molecular system depends on the level of the employed basis functions. The exponential laws describing the convergences of the calculated Hartree-Fock (HF) and electronic correlation energies of water molecules have been determined by fitting the energies predicted by the CCSD(T) theory with various levels of correlation consistent basis functions. The law was applied to calculate the energies of a few simple water clusters by varying the OH bond distance of a molecule in order to understand how the two parts of the potential energy subject to the stretching motion of water molecules depend on the variation of local environments. It is found that the HF energy strongly depends on the environments of a local OH bond while the correlation energy is almost insensitive to the neighboring molecules. This suggests that the HF theory may have a great advantage in saving computation time for efficient calculations of vibrational frequencies widely distributed due to the inhomogeneity in the local environments of water molecules in the condensed phases.
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