Biomedical Engineering Reference
In-Depth Information
4229.
3806.
3383.
2960.
2537.
2114.
1691.
1268.
845.8
422.9
0.000
-150.
30.05
210.4
390.7
571.1
751.4
931.8
1112.
1292.
1472.
1653.
-150.
30.05
210.4
390.7
571.1
751.4
931.8
1112.
1292.
1472.
1653.
4229.
3806.
3383.
2960.
2537.
2114.
1691.
1268.
845.8
422.9
0.000
cm
-1
Figure 7.8
Infrared spectrum of the BFPF Green Fluorescent Protein Chromophore
calculated with the M06-HF density functional and the MIDIY+ basis set.
With modern density functionals that explicitly include correlation, this
scaling factor is close to 1 and this can be an indication of the goodness
of a given functional. For the results presented here, it is remarkable that
the M06 and the local M06L predicted so well the IR spectrum of BFPF
Green Fluorescent Protein Chromophore in comparison with experi-
mental measures. Notwithstanding, these results should be taken with
care because the experimental spectrum has been taken from the solid,
while the present calculations have been done in the presence of ethanol
simulated through a polarized continuum method. It should be noticed
that a recent work on the estimation of scaling factors for a large number
of density functionals have shown that functionals with low percentages
of HF exchange tend to predict more accurate frequencies [45].
h e calculation of the ultraviolet (UV-Vis) spectra of the studied system
has been performed by solving the time-dependent DFT (TD-DFT) equa-
tions according to the method implemented in Gaussian 09 [36, 46-48].
h e equations have been solved for 10 excited states.
h e absorption or UV-Vis spectra of the BFPF Green Fluorescent
Protein Chromophore molecule calculated with the M06, M06L, M06-2X
and M06-HF density functionals and the MIDIY+ basis sets are presented
in Figures 7.9 to 7.12, respectively. h e experimental absorption spectrum
of BFPF Green Fluorescent Protein Chromophore in ethanol has been
reported and displays the characteristics bands at 410 and 667 nm. All the
calculated spectra have the same shape and it is the same as for the experi-
mental absorption spectrum. However, there is a shit in each one of the
spectrum that can be related to the ammount of HF exchange that it is
included for every density functional considered in this study. h e func-
tional form of the M06, M06-2X and M06-HF functionals is the same, with
the only dif erence given by the aforementioned amount of HF exchange.
