Assessing configurational sampling in the quantum mechanics/molecular mechanics calculation of Temoporfin absorption spectrum and triplet density of states
EntityUAM. Departamento de Ingeniería Química
10.3390/molecules23112932Molecules 23 (2018): 2932
ISSN1420-3049 (print); 1420-3049 (online)
Funded byThis research was funded by the Innovative Training Network-European Joint Doctorates in Theoretical Chemistry and Computational Modelling TCCM-ITN-EJD-642294
SubjectsAbsorption properties; Configurational sampling; QM/MM; Temoporfin; Química
Rights© 2018 by the authors.
Esta obra está bajo una Licencia Creative Commons Atribución 4.0 Internacional.
The absorption properties of Temoporfin, a second-generation photosensitizer employed in photodynamic therapy, are calculated with an electrostatic-embedding quantum mechanics/molecular mechanics (QM/MM) scheme in methanol. The suitability of several ensembles of geometries generated by different sampling techniques, namely classical-molecular-dynamics (MD) and QM/MM-MD thermal sampling, Wigner quantum sampling and a hybrid protocol, which combines the thermal and quantum approaches, is assessed. It is found that a QM description of the chromophore during the sampling is needed in order to achieve a good agreement with respect to the experimental spectrum. Such a good agreement is obtained with both QM/MM-MD and Wigner samplings, demonstrating that a proper description of the anharmonic motions of the chromophore is not relevant in the computation of the absorption properties. In addition, it is also found that solvent organization is a rather fast process and a long sampling is not required. Finally, it is also demonstrated that the same exchange-correlation functional should be employed in the sampling and in the computation of the excited states properties to avoid unphysical triplet states with relative energies close or below 0 eV.
Google Scholar:De Vetta, Martina - Baig, Omar - Steen, Dorika - Nogueira, Juan J. - González, Leticia
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