Anomalous Temperature Dependence of the Lowest-Frequency Lattice Vibration in Crystalline γ-minobutyric Acid

Sara J. Dampf, Timothy Michael Korter

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Crystalline γ-aminobutyric acid (GABA) exhibits unusual thermal behavior in a low-frequency lattice vibration that occurs at 37.2 cm -1 at 290 K but decreases dramatically by 34.0% when the sample is cooled to 78 K. Lattice vibrations in molecular crystals are indicators of intermolecular force characteristics, and the extraordinary temperature sensitivity of this vibration offers new insight into the local environment within the solid. Solid-state density functional theory simulations of the GABA crystal have found this anomalous frequency shift is based in unexpected differences in the strengths of the intermolecular hydrogen bonds that are cursorily the same. This was accomplished through mapping of the potential energy surfaces governing the terahertz-frequency motions of the GABA solid and use of the quasi-harmonic approximation to model the response of all the lattice vibrations to temperature-induced unit cell volume changes brought about through the anharmonic character of the intermolecular interactions. The analysis reveals that the vibration in question is rotational in nature and involves the significant distortion of a specific weak intermolecular N-H···O hydrogen bond in the crystal that results in its unique thermal response.

Original languageEnglish (US)
Pages (from-to)2058-2064
Number of pages7
JournalJournal of Physical Chemistry A
Volume123
Issue number10
DOIs
StatePublished - Mar 14 2019

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Lattice vibrations
lattice vibrations
gamma-Aminobutyric Acid
Crystalline materials
low frequencies
temperature dependence
acids
Acids
Hydrogen bonds
hydrogen bonds
crystals
Aminobutyrates
Molecular crystals
vibration
Potential energy surfaces
Crystals
intermolecular forces
Temperature
frequency shift
Density functional theory

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry

Cite this

Anomalous Temperature Dependence of the Lowest-Frequency Lattice Vibration in Crystalline γ-minobutyric Acid. / Dampf, Sara J.; Korter, Timothy Michael.

In: Journal of Physical Chemistry A, Vol. 123, No. 10, 14.03.2019, p. 2058-2064.

Research output: Contribution to journalArticle

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AB - Crystalline γ-aminobutyric acid (GABA) exhibits unusual thermal behavior in a low-frequency lattice vibration that occurs at 37.2 cm -1 at 290 K but decreases dramatically by 34.0% when the sample is cooled to 78 K. Lattice vibrations in molecular crystals are indicators of intermolecular force characteristics, and the extraordinary temperature sensitivity of this vibration offers new insight into the local environment within the solid. Solid-state density functional theory simulations of the GABA crystal have found this anomalous frequency shift is based in unexpected differences in the strengths of the intermolecular hydrogen bonds that are cursorily the same. This was accomplished through mapping of the potential energy surfaces governing the terahertz-frequency motions of the GABA solid and use of the quasi-harmonic approximation to model the response of all the lattice vibrations to temperature-induced unit cell volume changes brought about through the anharmonic character of the intermolecular interactions. The analysis reveals that the vibration in question is rotational in nature and involves the significant distortion of a specific weak intermolecular N-H···O hydrogen bond in the crystal that results in its unique thermal response.

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