R: "{\\bf R}",
                tt: "{\\bf t}",
                GG: "{\\bf G}",
                kk: "{\\bf k}",
                qq: "{\\bf q}",
                kq: "{\\kk + \\qq}",
                qG: "{\\bf q + G}",
                kG: "{\\bf k + G}",
                kmq: "{\\kk - \\qq}",
                kpq: "{\\kk + \\qq}",
                kpG: "{\\kk + \\GG}",
                qpG: "{\\qq + \\GG}",
                nk: "{n \\kk}",
                mk: "{, \\kk}",
                nks: "{n \\kk\\sigma}",
    