Neutron and nuclear matter in Jastrow variational approach

The 'factor cluster' expansion method (FIY) developed by Clark and Ristig, which furnishes a powerful device for the calculations of the expectation values of the observables of a many-fermion system with respect to dynamically correlated state vectors, is briefly discussed. Attempts to calculate the equation of state of a uniform extended system of neutrons interacting by the Reid potential within the Jastrow variational framework due to Clark and his associates and other groups, met with limited success. All results however clearly reveal that, truncations at low cluster order even with 'suitable' constraints are only of limited value and break down at high densities. Extended system of neutrons should be studied now a days by employing hypernetted-chain procedures or more highly summed expansions. The problem of lowest order cluster calculations in nuclear matter is however different. Here one wishes to develop simple but efficient cluster approximations in low order with suitable constraints for nuclear matter at reliable density aiming to develop practical methods for dealing with finite nuclei (where fancy HNC methods cannot be used). The problem of inclusion of tensor force in nuclear matter calculations within the Jastrow variational approach is also discussed. (auth.)