Immiscible fluid displacement in porous media occurs several natural and industrial processes. For example, during petroleum extraction from rock reservoirs, water is used to displace oil. In this paper, we investigate the primary drainage imbibition a heterogeneous medium using an improved numerical model based on multicomponent pseudopotential lattice Boltzmann method. We apply recent develop...

In a recent Letter [1] Öğüt, Chelikowsky, and Louie (OCL) calculated the optical gap of Si nanocrystals as ε g,OCL = ε qp g,LDA − E e−h Coul, where ε qp g,LDA is the quasi-particle gap in the local-density approximation (LDA) and E Coul is the electron-hole Coulomb energy. They argued that their method produces different results from conventional approaches (e.g. pseudopotential [2]). We show i...

We identify the shortcomings of existing ab initio quantum chemistry calculations for the hyperfine couplings in the recently characterized azafullerene, C59N. Standard gaussian basis sets in the context of all–electron calculations are insufficient to resolve the spin density near the cores of the atoms. Using the Projector Augmented Wave method implemented on top of a standard pseudopotential...

We present a comparative study on the quantum size effects in CdS and CdSe spherical dots, using first-principles derived semi-empirical pseudopotential method. Various properties including single-particle energy levels, characterization of individual electron wave functions, interband and intraband transitions, electron-hole Coulomb and exchange interactions, and excitonic band gap are investi...

In the analysis of nonlinear waves in plasma, especially for search periodic waves, shock and solitons, mechanical analogy methods are widely applicable. The most famous them is Sagdeev pseudopotential method. However, sometimes mathematical difficulties arise when deriving formulas pseudopotentials. author proposes three tricks to get around these obtain exact pseudopotentials cases where dire...

Notes on and testing results for the ABINIT PAW versions of the GBRV pseudopotential library.

We present a new technique to accelerate the convergence of the folded spectrum method in empirical pseudopotential band edge state calculations for colloidal quantum dots. We use bulk band states of the materials constituent of the quantum dot to construct initial vectors and a preconditioner. We apply these to accelerate the convergence of the folded spectrum method for the interior states at...

We present a method for constructing a pseudoelectric field at each point in space, which gives the force on a classical ion due to its local or nonlocal pseudopotential interaction with a quantum electronic system. Our derivation extends a classical reciprocity theorem used by Hellmann and Feynman for purely Coulombic interactions to a family of generalized electron-ion potentials, which are u...

the high pressure behavior of the structural and electronic properties of kc1 is studied with use of the density functional pseudopotential method within local-density approximation. atzero pressure, the rocksalt phase is found to be lower in energy than cscl structure. however, we predict a phase transition into csci structure at a pressure of about 1.5 gpa. the calculated ground state propert...