BeO分子激发态的多参考组态相互作用计算

运用含Davidson修正的多参考组态相互作用（MRCI＋Q）方法，在Ahlrichs型TZVP基组水平上对BeO分子对应最低3个离解限Be（1SG）＋0（3PG），Be（1SG）＋0（1DG），Be（3PU）＋O（3PG）的共14个单重态和12个三重态在0．1nm-0．5nm范围内进行了势能扫描计算．通过对称性分析，对这26个态进行了明确标识，其中有6个单重态和6个三重态为束缚态，它们分别是X1∑＋，A1∏，21∑＋，11’△，11∑-，21∏和a3∏，b3∑＋，23∑＋，13△，23∑-，23∑-．离解能最大的3个态分别为基态x1∑＋，第一单重激发态A1∏和三重态b3∑＋，离解能分别为5．878eV，4．876eV和4．311eV．21∏态的束缚能最小，仅为0．320eV．对所有的束缚态分别进行了振动能级和转动常数的计算，进而拟合出各自的光谱学常数．

MRCI Calculations for the Excited States of BeO Molecule

The potential energy curves （PECs） correlating to the lowest three dissociation limits Be Be（1SG）＋0（3PG）,Be（1SG）＋0（1DG）,Be（3PU）＋O（3PG）have been calculated by using m ulti-reference configuration interaction with Davidson correction （MRCI q- Q） method and the basis set of TZVP. Total- ly 14 singlet states and 12 triplet states PECs are canned with the internuclear distance range from 0.1 to 0. 5nm. According to the symmetry analysis,all the 26 states have been identified where the six singlet states X1∑＋,A1∏,21∑＋,11＇△,11∑-,21∏and the six triple states a3∏,b3∑＋,23∑＋,13△,23∑-,23∑- appear as the typical bound states. We get the dissociation energies for the ground state x1∑＋,the first singlet excit- ed state A1∏ and the triplet state ba∑＋ to be 5.878 eV,4.876 eV and 4.311 eV,respectively. The 21∏state has a shallow potential well with only 0.320 eV. Based on the PECs of the bound states,the possible vibra- tional levels and rotational constants are computed. Then the spectroscopic constants for these states are determined through spectral fitting method.