On the static electric polarizability and hyperpolarizability of sodium. How good is the agreement between theory and experiment for the dipole polarizability?

We have obtained accurate static electric polarizabilities and hyperpolariz abilities for the sodium atom. Relying on finite-field coupled-cluster (CC) calculations with large, systematically optimized basis sets of Gaussian-t ype functions we report values of 165.06 e(2)a(0)(2)E(h)(-1) for the dipole polarizability alpha, 1915.4 e(2)a(0)(4)E(h)(-1) for the quadrupole polari zability alpha (2), -66.1 x 10(3) e(3)a(0)(4)E(h)(-2) for the dipole-dipole -quadrupole hyperpolarizability B and 956 x 10(3) for the dipole hyperpolar izability It. The present theoretical dipole polarizability value is larger than all three available experimental estimates of this important property . The calculation of the dipole hyperpolarizability appears to be a problem of some difficulty, establishing the importance of reliable computational strategies for the determination of nonlinear optical properties of sodium clusters. (C) 2001 Elsevier Science B.V. All rights reserved.