Generates a simple plot of the quasiparticle weight decay curves given
       data object with doping setup

def plot_curves_z(data, name, title=None):
    """Generates a simple plot of the quasiparticle weight decay curves given
       data object with doping setup"""

    plt.figure()
    for zet, c in zip(data['zeta'], data['doping']):
        plt.plot(data['u_int'], zet[:, 0], label='$n={}$'.format(str(c)))
    if title != None:
        plt.title(title)
    label_saves(name+'.png')