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. Author manuscript; available in PMC: 2015 Oct 7.
Published in final edited form as: Phys Chem Chem Phys. 2013 Apr 19;15(25):10094–10111. doi: 10.1039/c3cp50439e

Table 1.

Theoreticala thermodynamic properties (kJ mol−1) of the glycine conformers.

Conformer Model T = 0 K
 T = 15 K
 T = 410 K
ΔEele best/DFTb ΔEele best/bestb Δ E ZPVE c ΔH ΔG ΔH ΔG
IIn/ccc HO 2.45 2.29 3.82 3.82 3.82 2.80 5.41
HO+HRd – – – 3.85 3.80 2.50 4.57
SPT(HRAO)d,e – – 3.73 3.77 3.72 2.45 4.41
Exp.f 1.38
IVn/gttg HO 4.89 4.87 4.81 4.81 4.81 4.59 5.97
HO+HRd – – – 4.82 4.82 4.68 5.99
SPT(HRAO)d,e – – 4.74 4.75 4.75 4.62 5.78
Exp.f 4.81
IIIp/tctg HO 7.42 7.44 7.48 7.59 7.34 7.61 −1.17
HO+HRd – – – 7.55 7.28 6.59 0.04
SPT(HRAO)d,e – – 7.94 7.90 7.87 6.62 9.72
Exp.h 5.8
Vn/gct HO 10.99 10.88 11.22 11.23 11.23 10.87 12.10
HO+HRd – – – 11.22 11.23 11.21 12.15
SPT(HRAOd,e) – – 11.21 11.21 11.22 11.21 12.02
VIp/ttci HO 20.34 20.32 19.39 19.89 19.89 20.02 20.34
HO+HRd – – – 19.80 19.77 20.08 20.24
SPT(HRAO)d,e – – 19.80 19.81 19.80 20.24 20.26
TS IIp/ccc 2.87 2.92
a

Conformational energies with respect to the Ip/ttt conformer. All thermodynamic properties have been computed at 1 atm.

b

“best/DFT” means CBS+CV energy computed at the DFT (B3LYP/SNSD) optimized geometry; “best/best” means CBS+CV energy computed at the corresponding optimized geometry.

c

ZPVE differences added to the ΔEele “best/best”.

d

The two lowest vibrations have been described by hindered-rotor contributions computed by an automatic procedure76.

e

Contributions computed by means of the HDCPT258 model using the hybrid CC/DFT force field, in conjunction with simple perturbation theory (SPT)58,86 (see text for the details).

f

Experimental gas-phase data from Ref.21, obtained from the Raman band ratios using the van’t Hoff scheme.

g

Ref.41.

h

Experimental low-temperature matrix data from Ref.15, obtained based on the integrated intensities of ν(C = O) from the samples evaporated at 358 K and 438 K.

i

Ref.40.