title: Characterization of the Elusive Conformers of Glycine from State-of-the-Art Structural, Thermodynamic, and Spectroscopic Computations: Theory Complements Experiment.
abstract: A state-of-the-art computational strategy for the evaluation of accurate molecular structures as well as thermodynamic and spectroscopic properties along with the direct simulation of infrared (IR) and Raman spectra is established, validated (on the basis of the experimental data available for the Ip glycine conformer) and then used to provide a reliable and accurate characterization of the elusive IVn/gtt and IIIp/tct glycine conformers. The integrated theoretical model proposed is based on accurate post-Hartree-Fock computations (involving composite schemes) of energies, structures, properties, and harmonic force fields coupled to DFT corrections for the proper inclusion of vibrational effects at an anharmonic level (as provided by general second-order perturbative approach). It is shown that the approach presented here allows the evaluation of structural, thermodynamic, and spectroscopic properties with an overall accuracy of about, or better than, 0.001 Å, 20 MHz, 1 kJ·mol(-1), and 10 cm(-1) for bond distances, rotational constants, conformational enthalpies, and vibrational frequencies, respectively. The high accuracy of the computational results allows one to support and complement experimental studies, thus providing (i) an unequivocal identification of several conformers concomitantly present in the experimental mixture and (ii) data not available or difficult to experimentally derive.
authors.affiliation: Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Barone
authors.affiliation: Center for Nanotechnology Innovation @NEST, Istituto Italiano di Tecnologia, Piazza San Silvestro 12, I-56127 Pisa, Italy.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Biczysko
authors.affiliation: Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126 Pisa, Italy.|Consiglio Nazionale delle Ricerche, Istituto di Chimica dei Composti OrganoMetallici (ICCOM-CNR), UOS di Pisa, Area della Ricerca CNR, Via G. Moruzzi 1, I-56124 Pisa, Italy.
authors.forename: Julien
authors.initials: J
authors.lastname: Bloino
authors.affiliation: Dipartimento di Chimica "G. Ciamician," Università di Bologna, Via F. Selmi 2, 40126 Bologna, Italy.
authors.forename: Cristina
authors.initials: C
authors.lastname: Puzzarini