A combined study on the skeletal vibration of aminopyrine by terahertz time-domain spectroscopy and DFT simulation

Fan, Heng; Liu, Mingming; Xie, MaoQiang; Liu, Weiwei; Sun, Lu

doi:10.1016/j.ijleo.2019.163913

Cited by 4 publications

(1 citation statement)

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“…It has been widely applied in the interpretation of the experimental observation of low-frequency vibrations of crystals. [30][31][32][33] The common process of THz spectrum calculation using DFT method is geometry optimization followed by phonon calculation. In geometry optimization, electronic energy is described as the function of nucleus position.…”

Section: Quasi-harmonic Approximation (Qha) Calculationsmentioning

confidence: 99%

Temperature‐Dependent Terahertz Spectra of Isonicotinamide in the Form I Studied Using the Quasi‐Harmonic Approximation

Sun

Lei

et al. 2022

ChemPhysChem

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Anharmonicity of molecular vibrational motions is closely associated with the thermal property of crystals. However, the origin of anharmonicity is still not fully understood. Lowfrequency vibrations, which are usually defined in the terahertz (THz) range, show excellent sensitivity to anharmonicity. In this work, anharmonicity of isonicotinamide in the form I was investigated by using temperature-dependent terahertz timedomain spectroscopy and the quasi-harmonic approximation (QHA) approach at PBE-D3 and PBE-MBD levels. Both DFT calculations suggest the variation of π-π stacking conformation dominates in the thermal expansion of the unit cell. Frequency shifts of the modes in THz range obtained by QHA approach are found to be qualitatively consistent with experimental observations, demonstrating QHA approach is a useful tool for the interpretation of frequency shifts of modes induced by temperature.

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Section: Quasi-harmonic Approximation (Qha) Calculationsmentioning

confidence: 99%