异核VMn氢化物稳定构型及金属间化学键

VMn hydride stable configurations and intermetallic bond

摘要:

用密度泛函DFT方法，相关泛函和交换泛函均采用PW91泛函，所有原子均采用DZP全电子极化基组，研究了VMnHx (x=1~5)系列分子的较低能量构型. 讨论了VMnHx (x=1~5)团簇分子的基态分子结构、红外光谱特征、热力学稳定性、及其金属间化学键. 结果表明：VMnHx (x=1~5)基态构型所属点群及电子态分别为：VMnH(Cs, 2A′ )、VMnH2 (Cs, 1A′)、VMnH3(Cs, 2A′′)、VMnH4 (C3v, 3A1 )和VMnH5 (C1, 2A). 其最高占据轨道(HOMO)与最低空轨道(LUMO)间能隙值均大于30 kcal•mol-1，其中最大为VMnH4 (60.2 kcal•mol-1)，最小的是VMnH (34.6 kcal•mol-1). 平均原子化能随着氢原子个数的增加而单调增加. 其电子亲和能最大都小于4 kcal•mol-1，对电子的吸附能力也很弱. VMnH4的VMn间金属间化学键为单键，其余金属间化学键均为三键.

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.