The potential energy surface of the Fe dimer is investigated on the basis of density functional theory in the generalized gradient approximation (GGA). Electron correlation effects are taken into account explicitly within the GGA+U approach. We find a value of 2.20 eV for the Coulomb repulsion parameter U to describe the Fe dimer best, yielding a 9 Sigma(g)- ground state with an interatomic sep...

We investigate the electronic and magnetic properties of NiS2, which, by varying the chemical composition substituting S by Se atoms or applying pressure, can be driven across various electronic and magnetic phase transitions. By combining several theoretical methods, we highlight the different role played by the chalcogen dimers and the volume compression in determining the phase transitions, ...

The quasiparticle band structure can be properly described by Hedin's GW approximation (GW), at a high computational cost. For gaps, semilocal density functionals up to the generalized gradient (GGA) level cannot compete with accuracy of hybrid-based approximations or GW. Meta-GGA strong dependence on kinetic energy ingredient potentially give wider gaps compared GGAs. recent TASK meta-GGA func...

Density functional theory (DFT) is the only quantum-chemical avenue for calculating thermochemical/kinetic properties of large polycyclic aromatic hydrocarbons (PAHs) such as graphene nanoflakes. Using CCSD(T)/CBS PAH isomerization energies, we find that all generalized gradient approximation (GGA) and meta GGA DFT functionals have severe difficulties in describing isomerization energies in PAH...

A previous NMR structure of the duplex 5'GGU GGA GGCU/PCCG AAG CCG5' revealed an unusually stable RNA internal loop with three consecutive sheared GA pairs. Here, we report NMR studies of two duplexes, 5'GGU GGA GGCU/PCCA AAG CCG5' (replacing the UG pair with a UA closing pair) and 5'GGU GAA GGCU/PCCG AAG CCG5' (replacing the middle GA pair with an AA pair). An unusually stable loop with three ...

We investigate gallium and nitrogen vacancies in gallium nitride (GaN) bulk and nanowires using self-interaction corrected pseudopotentials (SIC). In particular, we examine the band structures to compare and contrast differences between the SIC results and standard density functional theory (DFT) results using a generalized gradient approximation (GGA) (Perdew et al 1996 Phys. Rev. Lett. 77 386...

Ubiquitin (Ub) attachment to membrane proteins can serve as a sorting signal for lysosomal delivery. Recognition of Ub as a sorting signal can occur at the trans-Golgi network and is mediated in part by the clathrin-associated Golgi-localizing, gamma-adaptin ear domain homology, ARF-binding proteins (GGA). GGA proteins bind Ub via a three-helix bundle subdomain in their GAT (GGA and target of M...

We have systematically investigated the influence of oxygen vacancy defects on the structural, electronic and magnetic properties of La(1-x)Sr(x)MnO3 (x = 1/3) film by means of ab initio calculations using bare GGA as well as GGA+U formalism, in the latter of which, the on-site Coulombic repulsion parameter U for Mn 3d orbital has been determined by the linear response theory. It is revealed th...