Based on density functional theory (DFT)

the clusterNiCo2S4was optimized at B3LYP/Lan12dz level in order to determin eleven optimized configurations and analyze their polarity and bonding properties.The results showed that the polarity of configuration 1(3) is the largest and the polarity of configuration 4(3)is the smallest.In the bond length analysis

Ni-Co and Co-Co bonds have antagonistic effect

and Ni-S

Co-S and S-S bonds have synergistic effect. The bonding effect of the same metal atom is the best

and the same nonmetallic atom is the worst.In the bond level analysis

the bond levels of configuration 4(1)and configuration 6(1)are all positive

and the bonding strength is strong.The main chemical bond hybridization modes are obtained by density of states diagram analysis: in the triplet configurations

there are d-d and p-p hybridization in Ni-Co bond and Co-Co bond

p-d hybridization in Ni-S bond and Co-S bond

and p-p hybridization in S-S bond; in the singlet configurations

there is d-d hybridization in Ni-Co bond

Ni-S bond

Co-S bond

Co-Co bond and S-S bond

and p-p hybridization in Ni-Co bond.