title: Hyperpolarizability of GaAs dimer is not negative.
abstract: We present a systematic study of the static electric hyperpolarizability of Ga(2)As(2). The authors rely on finite-field high-level ab initio calculations with carefully optimized basis sets. Their best values for the mean and the anisotropy of the dipole polarizability are alpha=158.57 and Deltaalpha=130.33e(2)a(0) (2)E(h) (-1). For the hyperpolarizability we propose an estimate gamma=(155+/-15)x10(3)e(4)a(0) (4)E(h) (-3), which does not agree with the negative value predicted by Lan et al. [J. Chem. Phys. 124, 094302 (2006)]. Density functional theory based methods yield values close to those predicted by conventional ab initio methods. The (hyper)polarizability components are particularly enhanced along the direction defined by the Ga-Ga axis.
authors.affiliation: Department of Chemistry, University of Patras, GR-26500 Patras, Greece. maroulis@upatras.gr
authors.forename: George
authors.initials: G
authors.lastname: Maroulis
authors.forename: Panaghiotis
authors.initials: P
authors.lastname: Karamanis
authors.forename: Claude
authors.initials: C
authors.lastname: Pouchan