B_(12)C_xN_(12-x)(x=2,4)团簇的几何和电子结构

Geometric and electronic structures of B_(12)C_xN_(12-x)(x=2,4)clusters

用从头计算方法研究了B_(12)C_xN_(12-x)(x=2,4)笼的几何和电子结构.从B_(12)N_(12)中用C原子替换N原子得到B_(12)C_xN_(12-x),这样取代的结构中只含B—C和B—N键.在稳定结构中,C原子在四元环上,形成了B_2C_2和B_2N_2环.B_(12)C_2N_(10)的HOMO主要由C和N的2p轨道组成,LUMO位于-3.6eV处,主要由C的2p轨道组成.B_(12)C_4N_8的HOMO也主要由C和N的2p轨道组成,LUMO位于-4.1eV处,主要由C的2p轨道组成.在B_(12)N_(12),B_(12)C_2N_(10)和B_(12)C_4N_8中B原子上的电荷约为1.17e,C原子上的电荷为-0.75e.B_(12)N_(12),B_(12)C_2N_(10)和B_(12)C_4N_8的能带隙分别为6.84eV,3.50eV和2.82eV.

The geometry and electronic structure of B_(12)C_xN_(12-x)(x=2,4)cages are studied by ab initio calculations.The structure is generated by replacing N with C in the B_(12)N_(12) cage to ensure only B—C and B—N bonds are formed.C atoms in the tetragonal rings of the stable structure is formed B_2C_2 and B_2N_2 squares.The HOMO of B_(12)C_2N_(10) is mainly formed by 2 p of C and N,and LUMO is located at-3.6 eV,mainly formed by C2 p orbitals.The HOMO of B_(12)C_4N_8 is also formed by 2 p of C and N,LUMO is located at-4.1 eV,mainly formed by 2 p of C.The natural charge on N and C is about 1.17 eand-0.75 ein B_(12)N_(12),B_(12)C_2N_(10) and B_(12)C_4N_8.The energy gap of B12 N12,B12 C2 N10 and B_(12)C_4N_8 is 6.84 eV,3.50 eV and 2.82 eV respectively.