text: from pyscfad.pbc import gto
  from pyscfad.pbc import dft, df
  
  basis = 'gth-szv'
  pseudo = 'gth-pade'
  
  a = 5.431020511
  lattice = [[0., a/2, a/2],
            [a/2, 0., a/2],
            [a/2, a/2, 0.]]
  disp = 0.01
  atom = [['Si', [0., 0., 0.]],
          ['Si', [a/4+disp, a/4+disp, a/4+disp]]]
  
  cell = gto.Cell()
  cell.atom = atom
  cell.a = lattice
  cell.basis = basis
  cell.pseudo = pseudo
  cell.build()
  
  mf = dft.RKS(cell, exxdiv=None)
  mf.xc = 'pbe'
  mf.kernel()
  jac = mf.energy_grad()
  print(jac.coords)
  