Performs FIESTA (gw) run

def gw_run(self):
        """
        Performs FIESTA (gw) run
        """

        if self.folder != os.getcwd():
            init_folder = os.getcwd()
            os.chdir(self.folder)

        with zopen(self.log_file, 'w') as fout:
            subprocess.call(["mpirun", "-n", str(self.mpi_procs), "fiesta",
                             str(self.grid[0]), str(self.grid[1]),
                             str(self.grid[2])], stdout=fout)

        if self.folder != os.getcwd():
            os.chdir(init_folder)