Title: Ab initio modelling of calcium phosphate clusters and their vibrational spectra
Author(s):

	I.E.Boldeskul (IInstitute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40030 Sumy, Ukraine) ,
	L.F.Sukhodub (Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40030 Sumy, Ukraine) ,
	A.N.Kalinkevich (Institute of Applied Physics, National Academy of Sciences of Ukraine, 58 Petropavlovskaya Str., 40030 Sumy, Ukraine) ,
	V.D.Khavryutchenko (Institute of Sorption and Problems of Endoecology, National Academy of Sciences of Ukraine, 13 General Naumov Str., 03164 Kiev, Ukraine)

Calcium phosphate and hydroxylcalcium phosphate clusters that model amorphous phase elementary unit cells as well as their vibrational spectra were calculated by ab initio quantum chemical method using GAMESS code. Normal coordinate analysis was accomplished for phosphate anion, tricalcium phosphate and hydroxylapatite. Calculated IR-spectra and spectra of inelastic neutron scattering were defined in comparison with experimental data. It was shown that within the suggested approach, vibrational spectroscopy appears to be a reliable method of verifying the quantum chemical calculated structure versus the experimental data.

Key words: molecular simulation, cluster approximation, calcium phosphate, hydroxyapatite, normal coordinate analysis
PACS: 31.15.Ar, 61.46.Bc, 87.68.+z, 87.15.-v