Keywords: 
• 第一性原理 /
• Mg2 /
• Ni /
• Mg2NiH4 /
• 结构稳定性

Abstract: irst-principle calculations are carried out to investigate the energies and the electronic structures of Mg2 Ni alloy and its high/low temperature hydrides. Results show that strong bonding interaction between Mg and Ni atoms exists in the Mg2 Ni alloy. With H inserted, the charge transfer occurs from Mg to Ni-3d, which gives rise to a band gap between Ni-3d and Ni-4p orbitals. The interaction between Mg and Ni in LT/HT-Mg2NiH4 hydrides is weakened due to the covalent bonding between Ni-4s and H-1s. Therefore, it neads more energy to remove tt atoms from LT-Mg2NiH4 than from HT- Mg2NiH4, indicating that HT-Mg2NiH4 is more suitable for de-hydrogenation reaction while the LT-Mg2 NiH4 is suitable lot hydrogenation reaction.