def write_gibbs_temperature(self, filename='gibbs-temperature.dat'):
    w = open(filename, 'w')
    for i in range(self._len):
        w.write(('%20.15f %25.15f\n' % (self._temperatures[i], self._equiv_energies[i])))
    w.close()
def write_gibbs_temperature(self, filename='gibbs-temperature.dat'):
    w = open(filename, 'w')
    for i in range(self._len):
        w.write(('%20.15f %25.15f\n' % (self._temperatures[i], self._equiv_energies[i])))
    w.close()