title: Vibrational dynamics and heat capacity in polyglycine II.
abstract: The earlier works on the vibrational dynamics of polyglycine II (PG II) suffer from several infirmities, which not only suppress the dynamical nature of normal modes, but also lead to several incorrect assignments and interactive constants of the potential field. In this study, we have re-examined the phonon dispersion profiles of PG II using Higgs method for evaluation of phase-related normal modes and have attempted to remove the infirmities, as far as possible. The Wilson's GF matrix method combined with the Urey-Bradley force field has been used for normal mode analysis. This potential field leads to correct assignments of Raman, infrared and inelastic neutron scattering frequencies. Characteristic features of the dispersion curve (v versus delta/pi plot), such as repulsion and regions of high density-of-states have been interpreted. In addition, the heat capacity as a function of temperature has been obtained via density-of-states. It agrees well with the experimental data and is being reported for the first time.
authors.affiliation: Department of Physics, University of Lucknow, Lucknow 226 007, India.
authors.forename: Abhishek Kumar
authors.initials: AK
authors.lastname: Mishra
authors.forename: Mahendra
authors.initials: M
authors.lastname: Singh
authors.forename: Poonam
authors.initials: P
authors.lastname: Tandon
authors.forename: Vishwambhar Dayal
authors.initials: VD
authors.lastname: Gupta
mesh_terms: D010455:Peptides / Q000737:chemistry*; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods; D013059:Spectrum Analysis, Raman / Q000379:methods; D013816:Thermodynamics; D014732:Vibration
chemical_list: D010455:Peptides; C011080:polyglycine