Theoretical modeling of the terahertz spectrum of l-tyrosine leads to experimental verification of previously unobserved vibrational mode
Publication Name
Journal of Chemical Physics
Abstract
We have calculated the theoretical terahertz spectrum of the amino acid l-tyrosine using density functional theory (DFT). We tried two electron density functionals, Perdew-Burke-Ernzerhof (PBE) and PBE-d3. PBE-d3 includes dispersion corrections to build in van der Waals interactions, which play a role in intermolecular bonding. Both DFT models predicted a low-frequency mode that has not been previously reported. We designed an experiment to search for this mode. Using a deliberately thick sample, intense synchrotron radiation, low temperatures, and temperature variation has enabled us to observe a new resonance at 1.79 ±0.01 THz. While the PBE and PBE-d3 spectra are similar and both match the low-energy experimental data, overall the PBE-d3 appears to be slightly superior. Further refinement still of the functional may lead to even better agreement with experiment above 2.4 THz.
Open Access Status
This publication is not available as open access
Volume
159
Issue
10
Article Number
105103
Funding Sponsor
National Computational Infrastructure