We study the effect of functional groups (CH3*4, OCH3, CH3, Cl, CN, F*4) on the electronic transport properties of 1,4-benzenediamine molecular junctions using the non-equilibrium Green function method. Exchange and correlation effects are included at various levels of theory, namely density functional theory (DFT), energy level-corrected DFT (DFT+Σ), Hartree-Fock and the many-body GW approxima...

Abstract: The last decade has seen a continued development of better experimental techniques to measure equation-of-state (EOS) for various materials. These improvements of both static and shock-compression approaches have increased the accuracy of the EOS and challenged the complimentary theoretical modeling. The conventional modeling of EOS, at least at pressure and temperature conditions tha...

AIMS Advanced cardiac disease, entailing more hypertrophy, fibrosis, scarring, dilatation and conduction delays, poses the question of whether defibrillation thresholds (DFTs) increase as left ventricular ejection fraction (LVEF) decreases. This question has been approached indirectly or insufficiently in previous studies. In this study we add and expand on our previous work, stratifying DFT fo...

We report tests of secondand third-generation density functionals, for pure density functional theory (DFT) and hybrid DFT, against the BH6 representative barrier height database and the AE6 representative atomization energy database, with augmented, polarized double and triple zeta basis sets. The pure DFT methods tested are G96LYP, BB95, PBE, mPWPW91, VSXC, HCTH, OLYP, and OPW91 and the hybri...

A density functional theory (DFT) is presented for describing the distributions of small ions around an isolated infinitely long polyanionic DNA molecule in the framework of the restricted primitive model. The hard-sphere contribution to the excess Helmholtz energy functional is derived from the modified fundamental measure theory, and the electrostatic interaction is evaluated through a quadra...

Conventional density functional theory DFT fails for materials with strongly correlated electrons, such as late transition metal oxides. Large errors in the intra-atomic Coulomb and exchange interactions are the source of this failure. The DFT+U method has provided a means, through empirical parameters, to correct these errors. Here, we present a systematic ab initio approach in evaluating the ...

Projection-based embedding provides a simple and numerically robust framework for multiscale wavefunction-in-density-functional-theory (WF-in-DFT) calculations. The approach works well when the approximate DFT is sufficiently accurate to describe the energetics of the low-level subsystem and the coupling between subsystems. It is also necessary that the low-level DFT produces a qualitatively re...

The Empirical Tight Binding (ETB) method is widely used in atomistic device simulations. The reliability of such simulations depends very strongly on the choice of basis sets and the ETB parameters. The traditional way of obtaining the ETB parameters is by fitting to experiment data, or critical theoretical bandedges and symmetries rather than a foundational mapping. A further shortcoming of tr...

Orbital-free (OF) methods promise significant speed-up of computations based on density functional theory (DFT). In this field, the development of accurate kinetic-energy density functionals remains an open question. In this chapter we review the shell-correction method (SCM, commonly known as Strutinsky’s averaging method) applied originally in nuclear physics and its more recent formulation i...

AIMS To investigate the correlation between body weight and defibrillation threshold (DFT) for transvenous lead systems using a porcine model. METHODS AND RESULTS Twenty-eight pigs were anaesthetised and DFTs assessed in single and dual coil configurations using a four-reversal binary search method. DFT was correlated with body weight in the RV --> Can and RV --> SVC + Can configurations. A P...