UPDATE: small update in the code structure (simpler). Fixed a bug in the PAM code from get_energy.
small update: quick fix problem with search_mu and convergence criteria
Update: pam_getfunx.f
Small update: redefined naming conventino for param.dat--> variables.h and dimension.h
Small update: add iread>1 to read chemical potential from hamiltonian.restart only, to continue
the fixed density calculation from a previous solution with a different model parameter.