一种适用于原子团簇的多体展开新方案: 以氮团簇为例

多体展开方法虽然已经广泛地用于估算弱相互作用体系的能量，但是其并不适用于计算共价团簇和金属团簇的能量. 本文提出了一种适用于计算共价体系能量的相互作用多体展开(IMBE)方法. 在相互作用多体展开方法中，体系的能量表示为孤立原子的能量及该原子与其他周围原子间相互作用的和. 首先将该方法应用于计算氮团簇的能量，且多体展开截断至四体项. 结果表明：与传统的多体展开方法相比，相互作用多体展开方法可以显著地降低能量误差. 另外，以密度泛函理论计算结果为参考，相互作用多体展开方法估算能量的误差不依赖于体系的大小和结构，说明相互作用多体展开方法比较适合用于估算共价相互作用大体系的能量.

A New Many-Body Expansion Scheme for Atomic Clusters: Application to Nitrogen Clusters

Although the many-body expansion (MBE) approach is widely applied to estimate the energy of large systems containing weak interactions, it is inapplicable to calculating the energies of covalent or metal clusters. In this work, we propose an interaction manybody expansion (IMBE) to calculate the energy of atomic clusters containing covalent bonds. In this approach, the energy of a system is expressed as the sum of the energy of atoms and the interaction energy between the atom and its surrounding atoms. The IMBE method is first applied to calculate the energies of nitrogen clusters, in which the interatomic interactions are truncated to four-body terms. The results show that the IMBE approach could significantly reduce the energy error for nitrogen clusters compared with the traditional MBE method. The weak size and structure dependence of the IMBE error with respect to DFT calculations indicates the IMBE method has good potential application in estimating energy of large covalent systems.