def get_pop(self, iteration=-1):
        """ """
        if iteration == -1:
            iteration = self.pdfparam.iterations
        self.cd_work_dir("get pop: iteration={}".format(iteration))

        run_type = "rks"
        pop_path = self.pdfparam.get_pop_mulliken_path(run_type, iteration=iteration)
        pop_vtr = pdf.Vector()
        pop_vtr.load(pop_path)

        self.restore_cwd()

        return pop_vtr