def internas_dihe(self, conex, ndih):
try:
self.qt_1 = self.dihedrals
self.dihedrals = [my.dihedros(self.cart[conex[i][0]-1], self.cart[conex[i][1]-1], \
self.cart[conex[i][2]-1], self.cart[conex[i][3]-1],self.qt_1[i]) for i in range(ndih)]
except AttributeError:
self.qt_1 = [0.0 for w in range(ndih)]
self.dihedrals = [my.dihedros(self.cart[conex[i][0]-1], self.cart[conex[i][1]-1], \
self.cart[conex[i][2]-1], self.cart[conex[i][3]-1],self.qt_1[i]) for i in range(ndih)]
