def fCoreRepulsion1(self, iAt, jAt):
    if (iAt == jAt):
        return 0.0
    (ChA, ChB) = [ElementNumbers[self.Elements[o]] for o in [iAt, jAt]]
    return ((ChA * ChB) / (np.sum(((self.Pos[:, iAt] - self.Pos[:, jAt]) ** 2)) ** 0.5))
def fCoreRepulsion1(self, iAt, jAt):
    if (iAt == jAt):
        return 0.0
    (ChA, ChB) = [ElementNumbers[self.Elements[o]] for o in [iAt, jAt]]
    return ((ChA * ChB) / (np.sum(((self.Pos[:, iAt] - self.Pos[:, jAt]) ** 2)) ** 0.5))