def plot_helmholtz_volume(self, thin_number=10, xlabel='Volume $(\\AA^3)$', ylabel='Free energy'):
    import matplotlib.pyplot as plt
    (fig, ax) = plt.subplots()
    self._plot_helmholtz_volume(ax, thin_number=thin_number, xlabel=xlabel, ylabel=ylabel)
    return plt
def plot_helmholtz_volume(self, thin_number=10, xlabel='Volume $(\\AA^3)$', ylabel='Free energy'):
    import matplotlib.pyplot as plt
    (fig, ax) = plt.subplots()
    self._plot_helmholtz_volume(ax, thin_number=thin_number, xlabel=xlabel, ylabel=ylabel)
    return plt