Ab-initio finite field SCF calculations with split valence double zeta basis set indicate that 9, 10- donor-acceptor substituted anthracene derivatives have large quadratic hyperpolarizabilities for suitable combinations of donor and acceptor moieties. A difference in the first hyperpolarizabilities (β_total) of isomeric organic chromophores containing the same donor and acceptor groups indicate the possible role of intramolecular charge transfer (ICT) in shaping the NLO response in these π-conjugated molecular chromophores. A correlation is sought to be established among calculated (β_total) on one hand and the donor strength, the strength of the acceptor, donor-acceptor interaction and the donor-acceptor separation, on the other by using Genetic Algorithm (GA) to search through the relevant parameter space. It appears that (β_total) of a molecule is dominantly determined by additive contributions from the donors and the acceptors. The results might be helpful in designing new NLO materials using the bichromophoric anthracene derivatives.