This work was supported by the Czech Science Foundation, projects no. GA17-12925S and GA17-14840S. The first author acknowledges the support by CEDAMNF project, reg. no. CZ. 02.1.01/0.0/0.0/15 003/0000358, co-funded by the ERDF as part of the Ministry of Education, Youth and Sports OP RDE programme.In the contribution, several approaches to evaluating this term will be analyzed
in terms of convergence properties and computing demands using test calculations on simple molecules of nitric oxide, carbon dioxide and tetrafluormethane, see Fig. 1, with interatomic distances scaled by a variable factor
