Study of P,T-Parity Violation Eects in Polar Heavy-Atom Molecules

Summary. Investigation of P,T-parity nonconservation (PNC) phenomena is of fundamental importance for physics. Experiments to search for PNC eects have been performed on TlF and YbF molecules and are in progress for PbO and PbF molecules. For interpretation of molecular PNC experiments it is necessary to cal-culate those needed molecular properties which cannot be measured. In particular, electronic densities in heavy-atom cores are required for interpretation of the mea-sured data in terms of the P,T-odd properties of elementary particles or P,T-odd interactions between them. Reliable calculations of the core properties (PNC eect, hyper ne structure etc., which are described by the operators heavily concentrated in atomic cores or on nuclei) usually require accurate accounting for both relativis-tic and correlation eects in heavy-atom systems. In this paper, some basic aspects of the experimental search for PNC eects in heavy-atom molecules and the com-putational methods used in their electronic structure calculations are discussed. The latter include the generalized relativistic eective core potential (GRECP) ap-proach and the methods of nonvariational and variational one-center restoration of correct shapes of four-component spinors in atomic cores after a two-component GRECP calculation of a molecule. Their eciency is illustrated with calculations of parameters of the eective P,T-odd spin-rotational Hamiltonians in the molecule