  Based on the mean-field determination of the single-particle energy in
nuclear matter that contains naturally a rearrangement term (RT) implied by the
Hugenholtz-van Hove theorem, the folding model of the nucleon optical potential
(OP) is extended to take into account the RT using the effective, density
dependent CDM3Yn interaction. With the exchange part of the nucleon folded OP
treated exactly in the Hartree-Fock manner, a compact nonlocal version of the
folding model is suggested in the present work to determine explicitly the
isospin-dependent, nonlocal central term of the nucleon OP. To solve the
optical model (OM) equation with a complex nonlocal OP, the calculable
$R$-matrix method is used to analyse the elastic neutron and proton scattering
on $^{40,48}$Ca, $^{90}$Zr, and $^{208}$Pb targets at low energies. The
inclusion of the RT into the folding model calculation of the nonlocal nucleon
OP was shown to be essential for the overall good OM description of elastic
nucleon scattering. To validate the nonlocal version of the folding model, the
OM results given by the nonlocal folded nucleon OP are also compared with those
given by the global parametrization of the nonlocal OP using the analytical
nonlocal form factor suggested by Perey and Buck.
