investigation of water cluster ((h2o)n , n = 2-6) in aspect of structures, energies and thermodynamic properties by ab initio methods

the intermolecular forces between water molecules are of great importance in many areas of chemistry including solvation, solution chemistry, and biochemistry. as a result of this (h2o)n systems have received a great significant of attention, both experimental and theoretical. all calculation of this study are carried out by gaussian 98 soft ware. geometry optimization for each cluster were be performed at hf/6-311++g(2df,2p), single point vibration energy b3lyp/6-311++g (2df,2p) and mp2/6-31+g(2df,p). ir frequencies and intensity were calculated at b3lyp/6-311++g (2df,2p) level of theory. all calculation was accomplished at 298 k and 0 k. the structures, energies and thermodynamic properties will be discussed.