Calculation of the Raman and IR frequencies as order parameters and the damping constant (FWHM) close to phase transitions in methylhydrazinium structures

KURT M., YURTSEVEN H. H., Kurt A.

JOURNAL OF MOLECULAR STRUCTURE, cilt.1181, ss.488-492, 2019 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 1181
  • Basım Tarihi: 2019
  • Doi Numarası: 10.1016/j.molstruc.2019.01.016
  • Dergi Adı: JOURNAL OF MOLECULAR STRUCTURE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.488-492
  • Anahtar Kelimeler: Order parameter, Damping constant, Raman and IR modes, Phase transition. MHyMn, METAL FORMATE FRAMEWORKS, TEMPERATURE-DEPENDENCE, PHONONS, LAMBDA
  • Orta Doğu Teknik Üniversitesi Adresli: Evet

Özet

Temperature dependences of the frequencies for the Raman modes of v (NH2), v(s) (CH3), v(1) (HCOO-), vs (CNN) and IR mode of rho (NH2) are calculated in particular, for MHyMn close to the phase transition temperature (T-C = 220 K) in the family of compounds CH3NH2NH2 M(HCOO)(3), MHyM with M = Mn, Mg, Fe and Zn. By assuming Raman and infrared frequency as an order parameter, this calculation is performed from the molecular field theory by using the experimental data from the literature. We also calculate the damping constant (FWHM) from the order parameter (Raman and IR frequency of those modes) by using the pseudospin (MHy(+) cations)-phonon coupled model (PS) and the energy-fluctuation model (EF) for methylhydrazinium metal formate frameworks. Expressions of the damping constant from both models are fitted to the observed FWHM data for the Raman and infrared modes studied for these metal formates.