old_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  from udkm1Dsim.atoms import Atom
  from udkm1Dsim.unitCell import UnitCell
  from pint import UnitRegistry
  u = UnitRegistry()
  u.default_format = '~P'
  
  
  def test_unit_cell():
      Dy = Atom('Dy')
      uc = UnitCell('uc', 'Unit Cell', 3.1*u.angstrom, heat_capacity=10*(u.J/u.kg/u.K),
                    lin_therm_exp=1e-6/u.K, therm_cond=1*(u.W/u.m/u.K),
                    opt_pen_depth=11*u.nm, sound_vel=5*(u.nm/u.ps))
      uc.add_atom(Dy, 'lambda strain: 0*(strain+1)')
      uc.add_atom(Dy, 'lambda strain: 0.5*(strain+1)')
  
      assert uc.id == 'uc'
      assert uc.name == 'Unit Cell'
      assert uc.a_axis == 3.1*u.angstrom
      assert uc.b_axis == 3.1*u.angstrom
      assert uc.c_axis == 3.1*u.angstrom
      assert uc.heat_capacity[0](300) == 10
      assert uc.int_heat_capacity[0](300) == 3000
      assert uc.lin_therm_exp[0](300) == 1e-6
      assert uc.int_lin_therm_exp[0](300) == 0.0003
      assert uc.therm_cond[0](300) == 1
      assert uc.opt_pen_depth == 11*u.nm
      assert uc.sound_vel == 5*(u.nm/u.ps)
      assert uc.get_property_dict(types='phonon') == {'_c_axis': 3.1e-10,
                                                      '_mass': 5.615766784599375e-26,
                                                      '_phonon_damping': 0.0,
                                                      'int_lin_therm_exp_str':
                                                          ['lambda T : 1.0e-6*T'],
                                                      'num_sub_systems': 1}
  
new_contents: #!/usr/bin/env python
  # -*- coding: utf-8 -*-
  
  from udkm1Dsim.atoms import Atom
  from udkm1Dsim.unitCell import UnitCell
  from pint import UnitRegistry
  u = UnitRegistry()
  u.default_format = '~P'
  from numpy import array
  
  
  def test_unit_cell():
      Fe = Atom('Fe')
      uc = UnitCell('uc', 'Unit Cell', 2.86*u.angstrom, heat_capacity=10*(u.J/u.kg/u.K),
                    lin_therm_exp=1e-6/u.K, therm_cond=1*(u.W/u.m/u.K),
                    opt_pen_depth=11*u.nm, sound_vel=5*(u.nm/u.ps))
      uc.add_atom(Fe, 'lambda strain: 0*(strain+1)')
      uc.add_atom(Fe, 'lambda strain: 0.5*(strain+1)')
  
      assert uc.id == 'uc'
      assert uc.name == 'Unit Cell'
      assert uc.a_axis == 2.86*u.angstrom
      assert uc.b_axis == 2.86*u.angstrom
      assert uc.c_axis == 2.86*u.angstrom
      assert uc.heat_capacity[0](300) == 10
      assert uc.int_heat_capacity[0](300) == 3000
      assert uc.lin_therm_exp[0](300) == 1e-6
      assert uc.int_lin_therm_exp[0](300) == 0.0003
      assert uc.therm_cond[0](300) == 1
      assert uc.opt_pen_depth == 11*u.nm
      assert uc.sound_vel == 5*(u.nm/u.ps)
      assert uc.get_property_dict(types='phonon') == {'_c_axis': 2.86e-10,
                                                      '_mass': 2.2674165653283783e-26,
                                                      '_phonon_damping': 0.0,
                                                      'int_lin_therm_exp_str':
                                                          ['lambda T : 1.0e-6*T'],
                                                      'spring_const': array([6]),
                                                      'num_sub_systems': 1}
  
subject: update unit_cell test from Dy to Fe