  We use a generalized Gutzwiller Approximation (GA) elaborated to evaluate
matrix elements with partially projected wave functions and formerly applied to
homogeneous systems.
  In the present paper we consider projected single-particle (hole) excitations
for electronic systems with antiferromagnetic (AFM) order and obtain the
corresponding tunnelling probabilities. The accuracy and the reliability of our
analytical approximation is tested using the Variational Monte Carlo (VMC).
Possible comparisons with experimental results are also discussed.
