title: Vibrational Spectroscopy and Phonon-Related Properties of the L-Aspartic Acid Anhydrous Monoclinic Crystal.
abstract: The infrared absorption and Raman scattering spectra of the monoclinic P21 l-aspartic acid anhydrous crystal were recorded and interpreted with the help of density functional theory (DFT) calculations. The effect of dispersive forces was taken into account, and the optimized unit cells allowed us to obtain the vibrational normal modes. The computed data exhibits good agreement with the measurements for low wavenumbers, allowing for a very good assignment of the infrared and Raman spectral features. The vibrational spectra of the two lowest energy conformers of the l-aspartic molecule were also evaluated using the hybrid B3LYP functional for the sake of comparison, showing that the molecular calculations give a limited description of the measured IR and Raman spectra of the l-aspartic acid crystal for wavenumbers below 1000 cm(-1). The results obtained reinforce the need to use solid-state calculations to describe the vibrational properties of molecular crystals instead of calculations for a single isolated molecule picture even for wavenumbers beyond the range usually associated with lattice modes (200 cm(-1) < ω < 1000 cm(-1)).
authors.affiliation: Universidade Estadual do Piauí , 64260-000 Piripiri, Pi Brazil.
authors.forename: A M
authors.initials: AM
authors.lastname: Silva
authors.affiliation: Departamento de Física, Universidade Federal do Ceará, Centro de Ciências , Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, CE Brazil.
authors.forename: S N
authors.initials: SN
authors.lastname: Costa
authors.affiliation: Departamento de Física, Universidade Federal do Ceará, Centro de Ciências , Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, CE Brazil.
authors.forename: F A M
authors.initials: FA
authors.lastname: Sales
authors.affiliation: Departamento de Física, Universidade Federal do Ceará, Centro de Ciências , Caixa Postal 6030, Campus do Pici, 60455-760 Fortaleza, CE Brazil.
authors.forename: V N
authors.initials: VN
authors.lastname: Freire
authors.affiliation: Departamento de Análises Clínicas e Toxicológicas, Universidade Federal do Ceará , Campus do Porangabuçu, 60430-270 Fortaleza, CE Brazil.
authors.forename: E M
authors.initials: EM
authors.lastname: Bezerra
authors.affiliation: Engenharia de Computação, Universidade Federal do Ceará , 62042-280 Sobral, CE Brazil.
authors.forename: R P
authors.initials: RP
authors.lastname: Santos
authors.affiliation: Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte , 59072-970 Natal, RN Brazil.
authors.forename: U L
authors.initials: UL
authors.lastname: Fulco
authors.affiliation: Departamento de Biofísica e Farmacologia, Universidade Federal do Rio Grande do Norte , 59072-970 Natal, RN Brazil.
authors.forename: E L
authors.initials: EL
authors.lastname: Albuquerque
authors.affiliation: Instituto Federal de Educação, Ciência e Tecnologia do Ceará, 60040-531 Fortaleza, CE Brazil.
authors.forename: E W S
authors.initials: EW
authors.lastname: Caetano
mesh_terms: D001224:Aspartic Acid / Q000737:chemistry*; D008968:Molecular Conformation; D060739:Phonons; D011789:Quantum Theory; D013057:Spectrum Analysis; D013059:Spectrum Analysis, Raman; D014732:Vibration
chemical_list: D001224:Aspartic Acid