An accurate description of the ground and excited states of SiH

摘要

The astrophysical importance of the SiH radical has motivated significant experimental and theoretical work.However,only the X~2II and A~2triangle open states of SiH have been extensively investigated experimentally,while the study of higher excited states is rather limited.From a theoretical point of view,most of the studies have been focused on spectroscopic and thermochemical quantities of the ground state.The lack of accurate spectroscopic parameters (r_e,D_e,#omega#_e,#omega#_ex_e,#alpha#_e,D_e,T_e)pertaining to higher excited states was the driving force of the present work,in line with our pertaining to higher excited states was the driving force of the present work,in line with our pevious study of the isovalent CH molecule [A.Kalemos,A.Mavridis,and A.Metropoulos,J.Chem.Phys.iii,9536(1999)],Using the multireference configuration interaction approach coupled with very large correlation-consistent basis sets,we have constructed potential energy curves for 18 molecular states correlating to Si(~3P,~1D,~1S,~3P,~1P)+H(~2S).At the same level,the potential energy curve of the ground SiH~+ state (X~1sum~+)has also been constructed.We report total energies,dissociation energies,and the usual spectroscopic constants for ~(28)Si-(~1,2)H and for all states studies.Most of our results are in excellent agreement with existing experimental values.In particular,we believe that our dissciation energy for the X state,D_e=73.28kcal/mol,is the most reliable reported so far in the literature.