A highly stable (H2O)(20)(-) dodecahedral cluster was identified by applying the density functional theory and 6-311++G** and aug-cc-pVDZ basis sets. This cluster has four non-H-bonding H atoms turned toward cavity and has vertical electron dissociation energy of around 1.32 eV. The examination of singly occupied molecular orbital suggests that the extra electron is located inside of the dodecahedral cage and is surrounded by 20 water molecules. Calculation of OH stretch frequencies suggests intensity maxima at around 2914 cm(-1) for inward turned H atoms and around 3073 cm(-1) for H-bonded H atoms. The six dangling H atoms (projected outward) show negligible intensity at around 3700 cm(-1). (C) 2004 Elsevier B.V. All rights reserved.