Abstract:Two possible structures of Mo₈O₂₆^4-) were optimized using the Polak-Ribiere method of Molecular Mechanics Optimization and the termination condition is RMS (Root-mean-square) gradient of 0.42kJ/mol. Based on the calculations of the molecular dynamics, Lengevin dynamics and Monte Carlo dynamics simulation, the structure models of Mo₈O₂₆^4- with the lowest energy were acquired respectively according to the energy of the systems calculated using the ZIDO/1 and PM3 methods. The total energy, energies of some frontier molecular orbitals and atomic charges of Mo₈O₂₆^4－ were computed at the HF/3-21G and HF/STO-3G levels. The calculation results show that the contortion of the structure with eight MoO₆ is smaller than that of the structure with six MoO₆ and two MoO₄. The total energies of the two structures are nearly equal because the contortion of the structure with six MoO₆ and two MoO₄ would make the exclusion force decreased.

Key words:  quantum chemistry calculation; Mo₈O₂₆^4-; structure