title: Lattice dynamics of coesite.
abstract: The lattice dynamics of coesite has been studied by a combination of diffuse x-ray scattering, inelastic x-ray scattering and ab initio lattice dynamics calculations. The combined technique gives access to the full lattice dynamics in the harmonic description and thus eventually provides detailed information on the elastic properties, the stability and metastability of crystalline systems. The experimentally validated calculation was used for the investigation of the eigenvectors, mode character and their contribution to the density of vibrational states. High-symmetry sections of the reciprocal space distribution of diffuse scattering and inelastic x-ray scattering spectra as well as the density of vibrational states and the dispersion relation are reported and compared to the calculation. A critical point at the zone boundary is found to contribute strongly to the main peak of the low-energy part in the density of vibrational states. Comparison with the most abundant SiO2 polymorph--α-quartz--reveals similarities and distinct differences in the low-energy vibrational properties.
authors.affiliation: European Synchrotron Radiation Facility, BP 220 F-38043 Grenoble Cedex, France. wehinger@esrf.fr
authors.forename: Björn
authors.initials: B
authors.lastname: Wehinger
authors.forename: Alexeï
authors.initials: A
authors.lastname: Bosak
authors.forename: Aleksandr
authors.initials: A
authors.lastname: Chumakov
authors.forename: Alessandro
authors.initials: A
authors.lastname: Mirone
authors.forename: Björn
authors.initials: B
authors.lastname: Winkler
authors.forename: Leonid
authors.initials: L
authors.lastname: Dubrovinsky
authors.forename: Natalia
authors.initials: N
authors.lastname: Dubrovinskaia
authors.forename: Vadim
authors.initials: V
authors.lastname: Brazhkin
authors.forename: Tatiana
authors.initials: T
authors.lastname: Dyuzheva
authors.forename: Michael
authors.initials: M
authors.lastname: Krisch
mesh_terms: D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D011789:Quantum Theory; D011791:Quartz / Q000737:chemistry*; D012822:Silicon Dioxide / Q000737:chemistry*; D013816:Thermodynamics; D014732:Vibration; D014961:X-Ray Diffraction
chemical_list: D011791:Quartz; D012822:Silicon Dioxide