Structural and Energetic Study of Cisplatin and Derivatives: Comparison of the Performance of Density Funtional Theory Implementations

In this work, we compare the performance of different DFT implementations, using analytical and numerical basis sets for the expansion of the atomic wave function, in determining structural and energetic parameters of Cisplatin and some biorelevant derivatives. Characterization of the platinum-containing species was achieved at the HF, MP2, and DFT (PBE1PBE, mPW1PW91, B3LYP, B3PW91, and B3P86) levels of theory, using two relativistic effective core potentials to treat the Pt atom (LanL2DZ and SBK), together with analytical Gaussian-type basis sets as implemented in Gaussian03. These results were compared with those obtained with the SIESTA code that employs a pseudopotential derived from the Troullier−Martins procedure for the Pt atom and numerical pseudoatomic orbitals as basis set. All modeled properties were also compared with the experimental values when available or to the best theoretical calculations known to date. On the basis of the results, SIESTA is an excellent alternative to determine structure and energetics of platinum complexes derived from Cisplatin, with less computational efforts. This validates the use of the SIESTA code for this type of chemical systems and thus provides a computationally efficient quantum method (capable to linear scaling at large sizes and available in QM/MM implementations) for exploring larger and more complex chemical models which shall reproduce more faithfully the real chemistry of Cisplatin in physiological conditions.