In my Tesi di Laurea (equivalent to M.Sc. Diploma Thesis) in 1992, I have for the first time investigated and attempted the combination MD simulations and theoretical spectra calculation for the interpretation of experimental XANES (X-ray Absorption Near-Edge Spectroscopy) [4]. The method was used to study the crystal structure of the aquatrisimidazole copper (II) sulfate complex, but the results not yet published. The thesis is in Italian, and it is available on request to the interested reader.
Figure 2: Crystal structure of the aquatrisimidazole copper (II) sulfate complex.
We have also proposed and applied a novel approach to combine MD simulations to the refinement of experimental data from Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy on the analysis of different molecular systems [1,2,3]. In this approach (see schema below) MD simulations are used to obtain a model of pair distribution functions between the central photo-absorber and the surrounding scattering atoms. The distributions functions were used as a starting model to refine the experimental. The same procedure was used to validate intermolecular potential models used in the MD [3]. The method was applied to the study of an aqueous solution of ions and small molecules and can be extended to more complex systems like metalloproteins, inorganic complexes, and organometallic [4] compounds. These studies were the first example of the use of MD simulations to the interpretation and refinement of EXAFS experimental data.
REFERENCES
- D’Angelo, A. Di Nola, A. Filipponi, N. V. Pavel, D. Roccatano. An extended X-ray absorption fine structure study of aqueous solutions. J. Chem. Phys., 100, 985-994 (1994).
- D’Angelo, N. V. Pavel, H. F. Nolting, D. Roccatano. Multielectron excitations at the L-edges of barium in aqueous solution. Phys. Rev. B, 54, 12129-12138 (1996).
- Roccatano, H. J. C. Berendsen, P. D’Angelo. Assessment of the validity of intermolecular potential models used in molecular dynamics simulations by extended X-ray absorption fine structure spectroscopy: A case study of Sr in methanol solution. J. Chem. Phys., 108, 9487-9497 (1998).
- Roccatano. Determinazione della struttura dello Cu(II) aquatrisimidazolo solfato mediante dinamica molecolare e spettroscopia XANES. Tesi di Laurea, equivalent to a Master Thesis (in Italian). Advisors: Prof’s A. Di Nola and M. Barteri, Rome 1992.
