Anharmonic OH vibrations in Mg(OH)(2) (brucite): Two-dimensional calculations and crystal-induced blueshift
2009 (English)In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 131, no 24Article in journal (Refereed) Published
A two-dimensional quantum-mechanical vibrational model has been used to calculate the anharmonic OH vibrational frequencies in the layered Mg(OH)(2) (brucite) crystal. The underlying potential energy surface was generated by density functional theory (DFT) calculations. The resulting OH frequencies are upshifted (blueshifted) by about +75 cm(-1) with respect to the gas-phase OH frequency (+120 cm(-1) in experiments; the discrepancy is mainly due to inadequacies in the DFT and pseudopotential models). The Raman-IR split is about 50 cm(-1), both in the calculations and in experiments. We find that the blueshift phenomenon in brucite can qualitatively be explained by a parabolalike "OH frequency versus electric field" correlation curve pertaining to an OH- ion exposed to an electric field. We also find that it is primarily the neighbors within the Mg(OH)(2) layer that induce the blueshift while the interlayer interaction gives a smaller (and redshifting) contribution.
Place, publisher, year, edition, pages
2009. Vol. 131, no 24
anharmonic lattice modes, density functional theory, infrared spectra, potential energy surfaces, Raman spectra, spectral line shift, vibrational modes, initio total-energy, periodic hartree-fock, wave basis-set, ab-initio, neutron-diffraction, molecular-dynamics, infrared-spectra, hydroxide, pressure, gpa
IdentifiersURN: urn:nbn:se:kth:diva-19092DOI: 10.1063/1.3266507ISI: 000273217000047ScopusID: 2-s2.0-73649105477OAI: oai:DiVA.org:kth-19092DiVA: diva2:337139
QC 201005252010-08-052010-08-052010-12-23Bibliographically approved