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A comparison of different many‐body perturbation theory calculations of the ground state of SiS
Author(s) -
Lima Eneida G.,
Canuto Sylvio
Publication year - 1988
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560330503
Subject(s) - perturbation theory (quantum mechanics) , ground state , perturbation (astronomy) , third order , physics , statistical physics , computational chemistry , chemistry , quantum mechanics , philosophy , theology
A comparison of different many‐body perturbation theory ( MBPT ) calculations of the ground state rotational and vibrational constants of SiS is made. The calculations are performed up to the complete fourth‐order MBPT level, and in all cases two basis sets are utilized. The results of the third‐order and some incomplete fourth‐order calculations are in good agreement, but the complete fourth‐order is among the worst as compared with the experimental data. Analysis of the different contributions to the calculated correlation eneriges points towards the necessity of including even higher‐order terms of the( MBPT ) expansion.