Dipole Polarizability of Sodium

The possible origin of some discrepancy between the dipole polarizability of the sodium atom obtained from experimental studies and highly sophisticated atomic calculations, and its value computed by using 'molecular' methods of the electronic structure theory, is discussed. The extensive basis set saturation study shows that the earlier 'molecular' values are affected by the basis set deficiencies. The present scalar relativistic result calculated at the level of the coupled cluster (CCSD(T)) approximation is equal to 162.88 au and perfectly agrees with experimental (162.7 ± 0.8 au) and theoretical (162.6 ± 0.3 au, 163.06 au) atomic values. The present directly computed value also confirms the correctness of the earlier 'molecular' estimate (162.88 ± 0.6 au) obtained on the basis of extensive nonrelativistic CCSD(T) calculations.