Figure
3. Vibrational spectrum (with unscaled harmonic frequencies), for
global conformer EQ0#, computed at B3LYP-D3(BJ)/cc-PVTZ
level of the theory. The vertical solid lines (below the peaks) indicate
normal modes of vibrations (υ ), the details of which are provided
in Table 4 and SI Table S3.
Table 4. Characteristic unscaled harmonic
(v harm) and anharmonic
(v anharm) frequencies (in cm-1)
for global minimum conformer EQ0# of Leucine,
calculated at B3LYP-D3(BJ)/cc-pVTZ level of theory, at temperature of
298.15K. The experimental vibrational frequencies (indicated in bold)
are taken from a study by Stepanian et al (Ref. 30), and those in
italics are from a study by Linder et al (Ref. 31). For atom numbering
in the vibrational assignments of different modes, refer to Figure 1.
For the data on other species, see the supporting information.
(Assignment of modes, v : stretching, β: bending, τ: torsional, γ:
out of plane vibrations, asymm: asymmetric, sym: symmetric, + and –
sign represents the relative direction of vibration in a mode)