1 GRECP / RCC calculation of the spectroscopic constants for the HgH molecule and its ion

The Generalized Relativistic Effective Core Potential (GRECP) calculation of spectroscopic constants for the HgH molecule and its ion is carried out with the help of the Fock-space Relativistic Coupled Cluster (RCC) method. The Basis Set Superposition Errors (BSSE) are estimated and discussed. It is demonstrated that the triple cluster amplitudes at least for 13 external electrons should be taken into account in the precise calculations on mercury hydride. The spectroscopic constants derived from the potential curves corrected for these effects are in good agreement with the experimental data. The calculated spectroscopic constants are also compared with results of calculations of other groups.