cat >plotfile1<<!
plot "summary" using (\$1):(\$2)  w lp lt -1 lw 1 pt 4 lc -1 title "DFT"
!

cat >plotfile2<<!
plot "summary" using (\$1):(\$3+\$4)  w lp lt -1 lw 1 pt 4 lc 0 title "RPA"
!

gnuplot -persist plotfile1
gnuplot -persist plotfile2