Biomedical subjects

Pablo F Salazar

Publications and source records attributed to Pablo F Salazar.

3 recordsLinked to original sources

PubMed2006

Adsorption and dissociation of H2O2 on Pt and Pt-alloy clusters and surfaces.

The adsorption of H(2)O(2) on Pt and Pt-M alloys, where M is Cr, Co, or Ni, is investigated using density functional theory. Binding energies calculated with a hybrid DFT functional (B3PW91) are in the range of -0.71 to -0.88 eV for H(2)O(2) adsorbed with one of the oxygen atoms on top Pt positions of Pt(3), Pt(2)M, and PtM(2), and enhanced values in the range of -0.81 to -1.09 eV are found on top Ni and Co sites of the Pt(2)M clusters. Adsorption on top sites of Pt(10) yields a weaker binding of -0.48 eV, whereas on periodic Pt(111) and Pt(3)Co(111) surfaces, H(2)O(2) generally dissociates into two OH radicals. On the other hand, attempts to attach H(2)O(2) on bridge sites cause spontaneous dissociation of H(2)O(2) into two adsorbed OH radicals, suggesting that stable adsorptions on bridge sites are not possible for any of the clusters or extended surfaces that are being studied. We also found that the water-H(2)O(2) interaction reduces the strength of the adsorption of H(2)O(2) on these clusters and surfaces.

Adsorption↗

PubMed2006

Performance of multiplicity-based energy correctors for molecules containing second-row elements.

We introduce a posteriori multiplicity-based corrections to ab initio energies in order to reproduce experimental atomization energies. This simple approach, as compared to the alternative ones to improve density functionals and standard correlated methods, requires less computational resources than higher levels of theory. We extend our approach to include molecules containing second-row elements. Molecules are taken from the Gaussian sets for which experimental values are known with errors of less than 1 kcal/mol. We postulate that inexpensive multiplicity-based corrections can account for effects that are not accounted because of the low level of theory of the method or because of the small basis used for the calculations.

Journal Article↗

PubMed2006

Energy correctors for accurate prediction of molecular energies.

Energy correctors are introduced for the calculation of molecular energies of compounds containing first row atoms (Li-F) to modify ab initio molecular orbital calculations of energies to better reproduce experimental results. Four additive correctors are introduced to compensate for the differences in the treatment of molecules with different spin multiplicities and multiplicative correctors are also calculated for the electronic and zero-point vibrational energies. These correctors, individually and collectively yield striking improvements in the atomization energies for several ab initio methods. We use as training set the first row subset of molecules from the G1 basis of molecules; when the correctors are applied to other molecules not included in the training set, selected from the G3 basis, similar improvements in the atomization energies are obtained. The special case of the B3PW91/cc-pVTZ yields an average error of 1.2 kcal/mol, which is already within a chemical accuracy and comparable to the Gaussian-n theories accuracy. The very inexpensive B3PW91/6-31G** yields an average error of 2.1 kcal/mol using the correctors. Methods considered unsuitable for energetics such as HF and LSDA yield corrected energies comparable to those obtained with the best highly correlated methods.

Journal Article↗