Several first-principles calculations of positron-annihilation characteristics in solids have added gradient corrections to the local-density approximation within the theory by Arponen and Pajanne [Ann. Phys. (NY) 121, 343 (1979)] since this theory systematically overestimates the annihilation rates. As a further remedy, we propose to use gradient corrections for other local-density approximati...

The study of electronic excitations in hydrogen terminated silicon clusters is important for understanding the optical properties of confined systems such as quantum dots and porous silicon. Here we calculate the excitation energies and absorption spectra for SinHm clusters using linear response theory within the time-dependent local density approximation (TDLDA). We find the computed excitatio...

introduction :   co 2 (carbon dioxide) laser application in circumcision, for cutting and coagulation, has been reported to have excellent results. also, tissue glue has been reported to have advantages over sutures for approximation of wound edges. most previous studies focused on comparisons between co 2 laser and scalpel, or between tissue glue and sutures. this study prospectively compared ...

Doping evolution of the Fermi surface topology of Na(x)CoO(2) is studied systematically. Both local density approximation (LDA) and local spin density approximation (LSDA) predict a large Fermi surface as well as small hole pockets for doping levels x approximately 0.5. In contrast, the hole pockets are completely absent for all doping levels within LSDA+U. More importantly, we find no violatio...

The application of the density-functional theory in the local approximation to magnetic materials is discussed and illustrated by examples. The magnetic properties of the 3d elemental metals as well a s their cohesive properties are described by means of self-consistent local-spin-density (LSD) calculations and by using the LSD-Stoner method. The application of the LSD approximation to narrow-b...

We present a combined high-energy x-ray diffraction and local-density approximation study of the sodium ordering in Na(0.75)CoO2. The obtained results rule out previously proposed Na-ordering models and provide strong evidence for the formation of sodium-density stripes in this material. The local-density approximation calculations prove that the sodium-density stripes lead to a sizable dip in ...

N. Helbig,1 J. I. Fuks,1 M. Casula,2 M. J. Verstraete,3,4 M. A. L. Marques,5,4 I. V. Tokatly,1,6 and A. Rubio1,7 1Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento Fı́sica de Materiales, Universidad del Paı́s Vasco, CFM CSIC-UPV/EHU-MPC and DIPC, Avenida Tolosa 72, E-20018 San Sebastián, Spain 2CNRS and Institut de Minéralogie et de Physique des Milieux Condensés, c...

An approximate Kohn–Sham exchange-correlation potential nxc SAOP is developed with the method of statistical averaging of ~model! orbital potentials ~SAOP! and is applied to the calculation of excitation energies as well as of static and frequency-dependent multipole polarizabilities and hyperpolarizabilities within time-dependent density functional theory ~TDDFT!. nxc SAOP provides high qualit...

Abstract We discuss the crystal, electronic, and magnetic structures of La 2− x Sr CuO 4 (LSCO) for = 0.0 0.25 employing 13 density functional approximations, representing local, semi-local, hybrid exchange-correlation approximations within Perdew–Schmidt hierarchy. The meta-generalized gradient approximation (meta-GGA) class functionals is found to perform well in capturing key properties LSCO...