VMn hydride stable configurations and intermetallic bond

Abstract:

The lower energy stable geometric configurations of VMnHx (x=1-5) have been investigated by employing the hybrid density functional method (DFT) where the exchange-correlation functional in PW91 functional together with double-ζ polarization (DZP) basis sets are used. The properties of ground states also have been discussed. These properties include their ground state molecular stereo-structures and infrared spectral characters, thermodynamic stabilities and chemical bonds between metal atoms. The results show that: the point groups and their electronic states of these ground state molecules are VMnH(Cs, 2A′ ), VMnH2 (Cs, 1A′), VMnH3(Cs, 2A′′), VMnH4 (C3v, 3A1 ) and VMnH5 (C1, 2A), respectively. Their energy gaps between the highest occupied orbital (HOMO) and the lowest empty orbital (LUMO) are all bigger than 30 kcal•mol-1, the largest one is VMnH4 with 60.2 kcal•mol-1, and the lowest one is VMnH with 34.6 kcal•mol-1. The average atomization energies of VMnHx (x=1~5) increase monotonously as the number of hydrogen atoms increase. Their highest electron affinity is less than 4 kcal•mol-1, meaning that their adsorption capacity for electrons is very weak. The intermetallic bond in ground VMnH4 is a single bond, the other such bonds are triple bond.