Meson Resonances 2+, 1+, 0+ in the Higher Symmetry Theory

The conditions under which direct lattice sums of electric potential, field, and field gradient converge are discussed. The analogous conditions under which differences in these lattice sums, for two points in the crystal, converge are also outlined. These conditions are applied to direct lattice sum calculations in crystals in which the ideal lattice is distorted close to a defect of some kind. The conver- gence conditions are then applied to the case of determining the direct lattice sums in crystals in which higher symmetry properties can be invoked, which leads to a knowledge by inspection of the lattice sum at one point in the unit cell.

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Erratum: “Boundary based on exchange symmetry theory for multilevel simulations. I. Basic theory” [J. Chem. Phys. 139, 044120 (2013)]

The Journal of Chemical Physics ◽

10.1063/1.4821990 ◽

2013 ◽

Vol 139 (11) ◽

pp. 119901 ◽

Cited By ~ 2

Author(s):

Motoyuki Shiga ◽

Marco Masia

Keyword(s):

Chem Phys ◽

Basic Theory ◽

Symmetry Theory

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Temperature Dependent Raman Scattering in CsTiOAsO4 Single Crystal

MRS Proceedings ◽

10.1557/proc-398-661 ◽

1995 ◽

Vol 398 ◽

Author(s):

A.R. Guo ◽

C.-S. Tu ◽

Ruiwu Tao ◽

R.S. Katiyar ◽

Ruyan Guo ◽

...

Keyword(s):

Soft Mode ◽

Low Frequency ◽

High Mobility ◽

Vibrational Modes ◽

Frequency Range ◽

Temperature Dependent ◽

Higher Symmetry ◽

Phonon Spectra ◽

Symmetry Structure ◽

Increasing Temperature

ABSTRACTThe longitudinal (LO) and transverse (TO) A1 vibrational modes have been measured between 30-1200 cm−1 as a function of temperature (30–1240 K) for CsTiOAsO4 (CTA). The frequencies for all corresponding Raman components shifted to lower frequencies on increasing the temperature, however, there is no typical soft-mode like behavior observed in the measured frequency range. The relative intensities of the low frequency bands increase dramatically with increasing temperature due to high mobility of Cs+ ion. A higher symmetry structure taking place above 940K has been confirmed by changes in the phonon spectra.

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Dimorphic ThNi2P2 with BaCu2S2 and CaBe2Ge2 Type Structure

Zeitschrift für Naturforschung B ◽

10.1515/znb-1994-0812 ◽

1994 ◽

Vol 49 (8) ◽

pp. 1074-1080 ◽

Cited By ~ 14

Author(s):

Jörg H. Albering ◽

Wolfgang Jeitschko

Keyword(s):

Phase Transformation ◽

High Temperature ◽

Crystal Structures ◽

Type Structure ◽

Variable Parameters ◽

Higher Symmetry ◽

X Ray ◽

Coordination Numbers ◽

Structure Factors ◽

High Temperature Form

Two modifications of ThNi2P2 were prepared in a tin flux at 850 °C (α-ThNi2P2) and 1000 °C (β-ThNi2P2). The crystal structures of both modifications were refined from singlecrystal X-ray data. α-ThNi2P2 (BaCu2S2 type structure): Pnma. a = 819.69(5), b = 394.28(3), c = 981.54(7) pm. R = 0.028 for 32 variables and 654 structure factors: β-ThNi2P2 (CaBe2Ge2 type structure): P4/nmm, a = 408.5(1), c = 908.0(3) pm, R = 0.033 for 15 variable parameters and 261 F values. Although the two structures are closely related, they can be transformed into each other only by a reconstructive phase transformation. The differences and similarities of the two structures are discussed. The high temperature form has higher symmetry, a smaller number of variable positional parameters, and a tendency for higher coordination numbers.

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