title: A DFT study on the vibrational spectroscopy of protoporphyrin IX.
abstract: Infrared and Raman spectra of protoporphyrin IX were recorded. DFT quantum chemical calculations were performed. Optimised molecular geometry, electric charge distribution, vibrational force constants were computed. The normal coordinate analysis and the scaling of the force constants yielded all the necessary data for the simulation of the infrared and Raman spectra and the potential energy distribution calculations. The result was the interpretation of all vibrational modes of the molecule. Conclusions were drawn from the difficulties arisen during the assignment of the vibrational spectra of such large molecules.
authors.affiliation: Department of Physical Chemistry and Material Sciences, Budapest University of Technology and Economics, H-1521 Budapest, Budafoki út 8, Hungary. fbilles@mail.bme.hu
authors.forename: Ferenc
authors.initials: F
authors.lastname: Billes
authors.forename: Balázs
authors.initials: B
authors.lastname: Várady
mesh_terms: D002264:Carboxylic Acids / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D011524:Protoporphyrins / Q000737:chemistry*; D011758:Pyrroles / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014732:Vibration
chemical_list: D002264:Carboxylic Acids; D011524:Protoporphyrins; D011758:Pyrroles; C028025:protoporphyrin IX