## Computational procedure The Raman activities

The Raman activities (SRa) calculated with the same program [31] were converted to relative Raman intensities (IRa) using the following relationship derived from the intensity NVP-BEZ235 of Raman scattering [43] and [44]:equation(1)Ii=f(ν0-νi)4Si∗ νi[1-exp(-hcνi/kT)] -1where ν0 is the wavenumber of the exciting laser (in this work, we have used the excitation wavenumber ν0 = 9398.5 cm−1, which corresponds to the wavelength of 1064 nm of the Nd: YAG laser), νi is the vibrational wavenumber of the ith normal mode (in cm−1) and Si is anaphase the Raman scattering activity of the normal mode νi. f (a constant equal to 10−12) is a suitably chosen common normalization factor for all peak intensities. h, k, c and T are the Planck and Boltzmann constants, the speed of light and the temperature in Kelvin, respectively.

Results and discussion