docs: def get_energy_buckingham(structure, gulp_cmd='gulp',
                            keywords=('optimise', 'conp', 'qok'),
                            valence_dict=None):
      """
      Compute the energy of a structure using Buckingham potential.
  
      Args:
          structure: pymatgen.core.structure.Structure
          gulp_cmd: GULP command if not in standard place
          keywords: GULP first line keywords
          valence_dict: {El: valence}. Needed if the structure is not charge
              neutral.
      """
      gio = GulpIO()
      gc = GulpCaller(gulp_cmd)
      gin = gio.buckingham_input(
          structure, keywords, valence_dict=valence_dict
      )
      gout = gc.run(gin)
      return gio.get_energy(gout)