Density-fragment interaction approach for quantum-mechanical/molecular-mechanical calculations with application to the excited states of a Mg2+-sensitive dye

摘要: A density-fragment interaction (DFI) approach for large-scale calculations is proposed. The DFI scheme describes electron density between many quantum-mechanical (QM) fragments, which overcomes errors in electrostatic interactions with the fixed point-charge description conventional quantum-mechanical/molecular-mechanical (QM/MM) method. self-consistent method, a mean-field treatment of QM fragment interactions, was adopted to include equally fragments. As result, this method enables evaluation polarization effects solvent and protein surroundings. This combined not only functional theory (DFT) but also time-dependent DFT. In order evaluate DFI-QM/MM we have applied it excited states magnesium-sensitive dye, KMG-20. succeeds including predicting accurately spectral shift caused by Mg2+ binding.