old_contents: #!/usr/bin/env python
  
  '''
  Write orbitals, electron density, molecular electrostatic potential in
  Gaussian cube file format.
  '''
  
  import numpy as np
  from pyscf.pbc import gto, scf
  from pyscf.tools import chgcar
  
  #
  # Regular CHGCAR file for crystal cell
  #
  cell = gto.M(atom='H 0 0 0; H 0 0 1', a=np.eye(3)*3)
  mf = scf.RHF(cell).run()
  
  # electron density
  chgcar.density(cell, 'cell_h2.CHGCAR', mf.make_rdm1())
  
  # 1st MO
  chgcar.orbital(cell, 'cell_h2_mo1.CHGCAR', mf.mo_coeff[:,0])
  
  
  #
  # Extended mode to support molecular system. In this mode, a lattic was
  # generated and the molecule was placed in the center of the unit cell.
  #
  from pyscf import gto, scf
  mol = gto.M(atom='H 0 0 0; H 0 0 1')
  mf = scf.RHF(mol).run()
  
  # electron density
  chgcar.density(mol, 'mole_h2.CHGCAR', mf.make_rdm1())
  
  # 2nd MO
  chgcar.orbital(mol, 'mole_h2_mo2.CHGCAR', mf.mo_coeff[:,1])
  
new_contents: #!/usr/bin/env python
  
  '''
  Write orbitals, electron density in VASP CHGCAR format.
  '''
  
  import numpy as np
  from pyscf.pbc import gto, scf
  from pyscf.tools import chgcar
  
  #
  # Regular CHGCAR file for crystal cell
  #
  cell = gto.M(atom='H 0 0 0; H 0 0 1', a=np.eye(3)*3)
  mf = scf.RHF(cell).run()
  
  # electron density
  chgcar.density(cell, 'cell_h2.CHGCAR', mf.make_rdm1())
  
  # 1st MO
  chgcar.orbital(cell, 'cell_h2_mo1.CHGCAR', mf.mo_coeff[:,0])
  
  
  #
  # Extended mode to support molecular system. In this mode, a lattic was
  # generated and the molecule was placed in the center of the unit cell.
  #
  from pyscf import gto, scf
  mol = gto.M(atom='H 0 0 0; H 0 0 1')
  mf = scf.RHF(mol).run()
  
  # electron density
  chgcar.density(mol, 'mole_h2.CHGCAR', mf.make_rdm1())
  
  # 2nd MO
  chgcar.orbital(mol, 'mole_h2_mo2.CHGCAR', mf.mo_coeff[:,1])
  
subject: update chgcar example