Set fake upper/lower bands, useful to set the same energy
            range in the spin up/down bands when calculating the DOS

def set_upper_lower_bands(self,e_lower,e_upper):
        """
            Set fake upper/lower bands, useful to set the same energy
            range in the spin up/down bands when calculating the DOS
        """
        lower_band = e_lower*np.ones((1,self.ebands.shape[1]))
        upper_band = e_upper*np.ones((1,self.ebands.shape[1]))

        self.ebands = np.vstack((lower_band,self.ebands,upper_band))
        if isinstance(self.proj,np.ndarray):
            proj_lower = self.proj[:,0:1,:,:]
            proj_upper = self.proj[:,-1:,:,:]
            self.proj = np.concatenate((proj_lower,self.proj,proj_upper),axis=1)