BeH分子基态振动能级与光谱常数的理论研究
Theoretical study of vibrational energy levels and spectroscopic constants for the ground state of BeH molecule

利用Molpro程序包提供的多种方法及基组对BeH分子基态()进行优化计算，结果表明，当选用多参考组态相互作用(MRCI)方法和基组aug-cc-pVQZ进行优化计算时，得到的平衡核间距及离解能与实验值符合较好。在该方法下对BeH分子进行单点能扫描，将得到的分子势能代入分子核运动的Schrdinger方程，求解该方程获得了BeH分子态J=0时的12个振动态，对于每个振动态，分别计算了其振动能级、转动惯性常数及离心畸变常数，同时进一步导出的光谱常数也与实验值较为吻合。
Optimization calculation is performed using different basis sets and methods for the ground state()of BeH molecule. Result show that the multi-reference configuration interaction(MRCI) method with aug-cc-pVQZ basis set for BeH molecule is the best group for calculating the equilibrium geometry, the dissociation energy. Potential energy curve(PEC) of BeH molecule have been computed by MRCI/aug-cc-pVQZ. Based on the analytical PEC, 12 vibrational states (J=0) of the ground state of BeH molecule are obtained by numerically solving the radical Schrdinger equation of nuclear motion. For each vibrational state, the vibrational energy levels , inertial rotation constants and the centrifugal distortion constants are calculated. Spectroscopic constants are obtained by fitting to vibrational energy levels and inertial rotation constants . Result show that the calculations are in good agreement with the experimental data