Ab-initio molecular dynamics simulation of water clusters

Ab-initio molecular dynamics calculation for water monomer, dimer, trimer, and hexamer are performed at 0 K and 4-200 K with all-electron mixed-basis local density approximation. Calculation conditions with small unit cell, 18.3 a.u., and high cutoff energy, 17 Ry, gave more closed structure to those obtained in experiments and in other ab-initio calculations than the conditions with large cell, 28.4 a.u. and low cutoff energy, 7.2 Ry. Much lower cutoff energy, 5.6 Ry, could not represent hydrogen bonds correctly in a hexamer.