The number of absorption and Raman optical modes for each Wyckoff orbit in the high-temperature tetragonal (I4/mmm) parent lattice of the Ruddlesden-Popper compounds Ca3X2O7, with X=Mn or X=Ti is given. We analyze the effect of sequential perturbations which lower the symmetry to Cmcm and Cmc21 and finally include magnetic ordering. We determine the power law behavior (within mean field theory)...

The structure, elastic properties and electronic structure of Ti-Al intermetallics including Ti3Al (space group P63/mmc), TiAl I4/mmm) TiAl3 P4/mmm) are systematically studied by first-principles calculations. results show that can exist stably whether Cr replaces Ti or Al. ductility the alloy cannot be improved when is replaced in Cr-doped TiAl3. However, it Al, has better ductility. In Ti3Al,...

We study radiation-damage events in MgO on experimental time scales by augmenting molecular dynamics cascade simulations with temperature accelerated dynamics, molecular statics, and density functional theory. At 400 eV, vacancies and mono- and di-interstitials form, but often annihilate within milliseconds. At 2 and 5 keV, larger clusters can form and persist. While vacancies are immobile, int...

f(t) = Ffaxt, ù)2t, • • • , COmt) where F(0it • • • , 0m) is a continuous function of period 2T in 0V1 v = 1, • • • , m. The numbers wi, • • • , œm are called the basic frequencies of ƒ(/). We shall denote by Afai, • • • , o)m) the class of all functions ƒ for which F is real analytic. For simplicity of notation we set 0=(0i, • • • , 0m) and w=(coi, • • • , o)m) (then i4(a>i, • • • , com)=4(w) ...

The title salt, [Mn(C2H6OS)6]I4, is made up from discrete [Mn(DMSO)6]2+ (DMSO is dimethyl sulfoxide) units connected through non-classical hydrogen bonds to linear I42- tetra-iodide anions. The MnII ion in the cation, situated on a position with site symmetry -3., is octa-hedrally coordinated by O atoms of the DMSO mol-ecule with an Mn-O distance of 2.1808 (12) Å. The I42- anion contains a neut...

Oxytetracycline, one of the tetracycline family, is a broadspectrum antibiotic produced by different species of Streptenryces, namely Streptomyees rimosus, Streptonryces capuensis, Streptomyces henetus, and Struptomyces platensis (Finlay et al,i)), The antibiotic is active on Gram-pesitive and negative bacteria, spirochetes, rickettsiae, nd some viruses, Many workers2"i4) have studied factors a...

The crystal structure of the pristine (I) and aged (II) crystals of CH3NH3PbI3 (hereafter MAPbI3) hybrid organic-inorganic lead iodide has been studied at 293 K with high-precision single-crystal X-ray diffraction using a synchrotron light source. We show that (I) and (II) are characterized by an identical tetragonal unit cell but different space groups: I422 for (I) and P42212 for (II). Both s...

We derive the action for the non-abelian field theory living on parallel non-BPS D3-branes in type IIA theory on the orbifold T/I4(−1)L. The classical moduli space for the massless scalars originating in the “would be” tachyonic sector shows an interesting structure. In particular, it contains non-abelian flat directions. At a generic point in this branch of the moduli space the scalars corresp...