Do not waste time computing terms that give no contribution to the energy
(suggested by Marco Govoni)


git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@11100 c92efa57-630b-4861-b058-cf58834340f0
Explanation of an otherwise mysterious workaround, cortesy of Minoru Otani


git-svn-id: http://qeforge.qe-forge.org/svn/q-e/trunk/espresso@11101 c92efa57-630b-4861-b058-cf58834340f0