Within density functional perturbation theory using norm‐conserving pseudopotentials and a plane‐wave basis set calculations of phonon dispersion relations and densities of states of LiAlTe2, LiGaTe2 and LiInTe2 compounds being crystallized into the tetragonal chalcopyrite structure have been performed. Theoretical values of phonon mode frequencies in LiGaTe2 and LiInTe2 are in good agreement with the experimental data available for these crystals obtained by the methods of Raman and infrared spectroscopies. The similarity of the physical and chemical properties of the crystals concerned manifests itself in the similarity of their phonon spectra that are especially close to each other in low‐ and high‐frequency ranges. Phonon modes of the upper phonon band are predominantly caused by the lithium sublattice vibrations and have an upper bound of 350–370 cm–1. In a mid‐frequency range a significant downshift of the vibrational frequencies is observed on going from LiAlTe2 to LiGaTe2 and LiInTe2 that is a consequence of the third group cation mass reduction. From calculated electron density maps it follows that Li‐containing chalcopyrites are characterized by a less pronounced bond between the first group cation and anion as compared with the Cu‐ and Ag‐based analogs due to the absence of pd‐hybridization. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

No abstract

Calculations of energy band structure, density of states, electronic density, and chemical bond parameters for a series of MeN3, where Me = Na, K, Rb, Cs, Ag, T1 have been given. The density functional theory and pseudopotential technique in mixed basis have been used. The valence band has been shown to be essentially formed from azideion states for alkali metal azides. The conduction band contains two subbands separated by a band gap. The first band is responsible for the anion states, while the second one is responsible for the cation ones. Silver d-states and thallium s-states have been seen to change greatly the structure of both the valence and conduction bands for AgN3 and TINS, viz. the upper valence bands are of a mixed anion-cation nature, the conduction band bottom consists of cation states, but the anion contributions increase when the energy grows. IIJIOTHOCTU, MeTOAOM I I C e B~O n O T e H~a . J I a , B CMeIlIaHHOM 6 a s a c e . HOKaCaHO, 9 T O B a 3 w a X Il&3lOSHbIX MeTanJIOB BaJIeHTHaX 3 0 H a Cf$OpMUpOBaHa IIpeUMyQeCTBeHHO U 3 COCTOXHEIfi a3wn e p B W 3 0 H a O T B e q a e T SLHIIOHHbIM, BTOpaX KaTUOHHbIM COCTOXHUIIM. d-COCTOIIHIlrr Ag S-COC-TOIIHMX T1 CyQeCTBeHHO MeHXHlT KaK BZUIeHTHyIO 30HY, TaK M 30HY IIpOBOAUMOCTEI. B AgN3 U T1N3 BepXHUe B m e H T H b I e 30HbI UMeIOT aHUOH-KaTUOHHYHl IIpUpOgy, HHO 30HbI IIpOBOAUMOCTH OTBeYaeT KaTUOHHbIM COCTOXHUXM C HapaCTaHUeM BKnaAOB OT aHUOHHbIX n p U BO3paCTaHUU WoHa. 3 o~a II~OBOAI~MOCTU COCTOMT 113 R B~X nogio~, p a 3~e n e~~b 1 x s a n p e~~e~~b r~ V a c r K o M .3 H e p r a u .

No abstract

No abstract