Pachucki, KrzysztofCencek, WojciechKomasa, Jacek2011-12-062011-12-062005-05-08JOURNAL OF CHEMICAL PHYSICS Volume: 122 Issue: 18 Article Number: 184101http://hdl.handle.net/10593/1545Gaussian type wave functions do not reproduce the interparticle cusps which result in a slow convergence of the expectation values of the operators involved in calculations of the relativistic and QED energy corrections. Methods correcting this deficiency are the main topic discussed in this paper. Benchmark expectation values of the singular operators for several few-electron systems are presented.en-USsingular operatorsexponentially correlated Gaussian functionsintegral transform techniqueexpectation value identitydrachmanizationhydrogen moleculeberyllium atomhelium dimerArtykuł