Temperature Dependence in the Terahertz Spectrum of Nicotinamide: Anharmonicity and Hydrogen-Bonded Network

Abstract

We have investigated the terahertz-spectral property of nicotinamide focusing on the temperature dependence in the range of 14-300 K. We observed that almost all peaks in the terahertz spectrum of the nicotinamide crystal showed a remarkable shift with temperature, whereas the lowest-frequency peak at 34.8 cm showed a negligible shift with temperature. By analyzing the terahertz spectrum with the dispersion-corrected density functional theory calculations, we found that the difference in the temperature dependence of the peak shift is well understood in terms of the presence/absence of stretching vibration of the intermolecular hydrogen bond in the mode and the change of cell parameters. The anharmonicity in the dissociation potential energy of very weak intermolecular hydrogen bonding causes the remarkable peak shift with temperature in the terahertz spectrum of nicotinamide. This finding suggests that the assignment and identification of peaks in the terahertz spectrum are systematically enabled by temperature-dependent measurements.

Vibrational Response of Felodipine in the THz Domain: Optical and Neutron Spectroscopy Versus Plane-Wave DFT Modeling

“…While introducing the use of the analytical response scheme by Gonze and Baroni [37][38][39][52][53][54][55], this paper provides a proven numerical recipe for an accurate modeling of low-wavenumber phonon frequencies. This strategy has been followed with a number of examples presented in the literature, using CASTEP [30][31][32][33][105][106][107][108][109], QUAN-TUM ESPRESSO [106,[110][111][112][113][114], ABINIT [115][116][117], or VASP [118,119], and has been used in the present study. Instead of advocating any of the presented strategies, we further highlight the main differences and limitations of each approach as both have their pros and cons.…”

Assessment of the VDW interaction converting DMAPS from the thermal-motion form to the hydrogen-bonded form

“…Another issue in the THz spectroscopic study of amorphous system is the treatment of surrounding molecules in the calculation for peak assignments. We have studied intermolecular weak hydrogen bonding of crystalline compounds using THz spectroscopy with DFT calculations 30–33 and synchrotron FTIR microspectroscopy 34 . Nowadays, THz spectroscopic studies are well established for crystalline systems including microcrystalline powder samples and THz peaks due to intermolecular weak hydrogen bonding networks are obtained as coupled with intermolecular translation and rotation modes.…”

Temperature-Dependent Low-Frequency Vibrations of Thiamine Crystal Containing Hydrated Ions

“…The geometries were fully optimized for both the cell parameters and atomic coordinates without maintaining fractional coordinates during lattice changes under monoclinic constraints. The X-ray crystallographic structure data obtained for the monohydrate of 1 were used for the initial structure of geometry optimization, but the symmetric constraint was changed to P 1 except for α = γ = 90° to obtain a clear stretching vibration from the intermolecular hydrogen bonds . The vibrational frequencies of the normal modes were calculated at the Γ-point within the harmonic approximation by linear response theory (or density functional perturbation theory), which provides an analytical strategy for computing the second derivative of the total energy with respect to a given perturbation, with a q -vector grid of 0.05 Å –1 for interpolation.…”

“…The crystal structure by low-temperature X-ray crystallography and peak assignment by precise first-principles calculation with dispersion correction are provided. It is known that precise first-principles calculations with dispersion corrections for crystalline systems allow us to unambiguously assign the THz vibrations. , In addition, we incorporate relativistic effects into the present first-principles calculations, as the system contains heavier elements, namely, sulfur and chlorine. The crystalline monohydrate of 1 is considered a snapshot of the moment when water attacks the chloride ion in the initial stage of dissolution.…”