C 1s core photoemission of C

We make a theoretical study of the shake-up of the 1s photoemission of C60. The method takes into account the N-body reactions of the π and σ electrons which appear during the formation of the photoemission hole on one carbon atom. We analyze the origin of the satellite in the spectra due to transitions between N-body states. Our calculation shows that the satellite spectra is essentially given by N-body transitions which involve the creation of one or two electron-hole pairs. The method has been applied also to C48N12. The situation is more complex. The spectra of the two most stable species have been investigated. Moreover the influence on the spectra of the position of the hole created on the carbon atom in C48N12 has been examined (all the carbon positions are not equivalent for some isomers)

Structural, electronic, elastic, and thermal properties of CaNiH3 perovskite obtained from first-principles calculations

A theoretical study of the structural, elastic, electronic, mechanical, and thermal properties of the perovskite-type hydride CaNiH3 is presented. This study is carried out via first-principles full potential (FP) linearized augmented plane wave plus local orbital (LAPW+lo) method designed within the density functional theory (DFT). To treat the exchange-correlation energy/potential for the total energy calculations, the local density approximation (LDA) of Perdew-Wang (PW) and the generalized gradient approximation (GGA) of Perdew-Burke-Ernzerhof (PBE) are used. The three independent elastic constants (C 11, C 12, and C 44) are calculated from the direct computation of the stresses generated by small strains. Besides, we report the variation of the elastic constants as a function of pressure as well. From the calculated elastic constants, the mechanical character of CaNiH3 is predicted. Pertaining to the thermal properties, the Debye temperature is estimated from the average sound velocity. To further comprehend this compound, the quasi-harmonic Debye model is used to analyze the thermal properties. From the calculations, we find that the obtained results of the lattice constant (a 0), bulk modulus (B 0), and its pressure derivative () are in good agreement with the available theoretical as well as experimental results. Similarly, the obtained electronic band structure demonstrates the metallic character of this perovskite-type hydride