The Nsum file is doing the integration of different regions n, p, Nd(a) (activated dopant), Radiative, nonradiative, Auger, and, generation The format is
VG VD VS ∫alln(r)dr2 ∫allp(r)dr2 ∫allNd(r)dr2 ∫allRad(r)dr2 ∫allnonRad(r)dr2 ∫allAugernon(r)dr2 ∫allgeneration(r)dr2 ∫r1n(r)dr2 ∫r1p(r)dr2 ∫r1Nd(r)dr2 ∫r1Rad(r)dr2 ∫r1nonRad(r)dr2 ∫r1Augernon(r)dr2 ∫r1generation(r)dr2 ∫r2n(r)dr2 ...