A Local Structure Analysis of Molten Li2CO3 Using the Density Functional Theory

概要

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The structures having the minimum interaction energy of the Li2CO3 monomer, dimer, trimer and tetramer were derived using the density functional theory (DFT). The structures of the monomer and the dimer agreed with the ab initio molecular orbital calculation results at a Hartree—Fock level. The structures of the trimer and the tetramer model were C3h and C2 symmetry, respectively. Then we carried out the harmonic frequency analysis of these geometries. The tetramer model showed the best agreement among these results with the Raman spectrum of the liquid state. On the other hand, we calculated the total structure factor S(Q) of the trimer and tetramer geometries considered from the DFT calculation to examine the local structure of molten Li2CO3. The calculation result corresponding to the tetramer model reproduced satisfactorily the position and the height of the S(Q) peaks. It was found that the DFT calculation of the tetramer model reproduced the S(Q) at the small Q region where the intermolecular correlations predominated.