TOOLS
NMR Relaxation Rates from Molecular Dynamics Simulation
Goncalves, M.A.; Santos, L.S. ; Peixoto, F.C.; Ramalho, T.C. Int. J. Quant. Chem. (2019) 119, e25896
DOI: https://doi.org/10.1002/qua.25896
Optimal Wavelet Signal Compression Algorithm (OWSCA)
Aiming, to reduce the number of QM calculations without loss of the relevant information from the simulation, a new method based on the wavelet analysis for selecting MD conformations had been developed, optimal wavelet signal compression algorithm (OWSCA). The time series data of MD conformations are used as an input for the OWSCA.
Firstly, in the wavelet transform, the original data set is decomposed into different frequencies, allowing a more precise evaluation of the MD conformation profiles. Secondly, in the wavelet compression, the decomposed data set of MD conformations is compressed, according to a particular compression rule. This step is crucial because an optimization procedure is conducted, allowing to select the best MD conformations which represents the most significant part of the data set. A genetic optimization algorithm was used for this purpose.
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Description of OWSCA:
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Gonçalves, M.A., Santos, L.S., Prata, D.M., Peixoto, F.C., da Cunha, E.F. F. Ramalho, T.C. Theor Chem Acc (2017) 136: 15.
Quantification of molecular orbitals based on projection operators
In recent decades, a large body of research has performed about chemical reactivity and Quantum Mechanics has arisen playing a vital role in this field. However, even with, the success of the HOMO-LUMO approach, many researchers wondered if these two orbitals would be the only responsible for molecules reactivity. Fukui has also exposed this concern in an article he wrote in commemoration of his Nobel Prize. In the face of such limitations, another approach arose to understand the chemical reactivity: the FERMO (Frontier Effective for Reaction Molecular Orbital) concept. Our strategy to quantify the FERMO localization is based on the use of projection operators as follows.
Braga, L.S.; Moreira, R.A.; Leal, D.H.S. ; Ramalho, T.C. Chem. Physics Let. (2019) 726, 87-92 DOI: