Fractional partial negative surface area 

Definition:

PNSA1 – partial negatively charged molecular surface area

TMSA - total molecular surface area

Reference:

1. D.T. Stanton, P.C. Jurs, Anal. Chem., 1990 62, 2323; D.T. Stanton, L.M. Egolf, P.C. Jurs, M.G. Hicks, J. Chem. Inf. Comput. Sci., 1992 32, 306.