Hubbard-U Band-Structure Methods (2009)
Albers, R. C., Christensen, N. E., Svane, A.
The last decade has seen a large increase in the number of electronic-structure calculations that involve adding a Hubbard term to the local density approximation band-structure Hamiltonian. The...
Vaitheeswaran, G., Kanchana, V., Kumar, Ravhi. S., Cornelius, A. L., Nicol, M. F., Svane, A., ...
The structural behaviour of CsCdF3 under pressure is investigated by means of theory and experiment. High-pressure powder x-ray diffraction experiments were performed up to a maximum pressure of 60...
Chantis, A. N., Albers, R. C., Svane, A., Christensen, N. E.
We present results for the electronic structure of plutonium by using a recently developed quasiparticle self-consistent $GW$ method (\qsgw). We consider a paramagnetic solution without spin-orbit...
We have calculated the spin--orbit splittings of the top valence bands of AlN, GaN and InN crystallized in the zinc blende structure, using the LMTO--LDA method. Because of the large differences in...
COMPUTER SIMULATIONS OF DEFECTS IN PEROVSKITE KNbO (2007)
Crystals Eglitis Kotomin, R. I. Eglitis, E. A. Kotomin, A. V. Postnikov, N. E. Christensen, M. A. Korotin, ...
INTRODUCTION Perovskite KNbO 3 crystals are widely used in non-linear optics and holography. Their properties are influenced by point defects, primarily by vacancies. Relatively little is known about...
Phonons and Phase Transitions in GaN (2007)
Christensen And, N. E. Christensen, P. Perlin
Experimental and theoretical studies of structural and vibrational properties of GaN are discussed. High-resolution x-ray scattering techniques are applied to single crystalline samples and they...
Solids under Pressure. Ab Initio Theory. (2007)
Christensen Novikov, N. E. Christensen, D. L. Novikov, R. E. Alonso, C. O. Rodriguez, Nacional La Plata
Parameter-free calculations based on the density-functional theory are used to examine high-pressure phases of solids, mainly semiconductors. For the elemental semiconductors, as represented by Si,...
Theory of point defects in GaN, AlN and BN: Relaxation and pressure effects (2007)
Gorczyca Svane, I. Gorczyca, A. Svane, N. E. Christensen
Native defects and some common dopants in cubic GaN, AlN and BN are examined by means of ab initio calculations using a supercell approach in connection with the full-potential linear...
Electronic structure of rare-earth impurities in GaAs and GaN (2006)
Svane, A., Christensen, N. E., Petit, L., Szotek, Z., Temmerman, W. M.
The electronic structures of substitutional rare-earth (RE) impurities in GaAs and cubic GaN are calculated. The total energy is evaluated with the self-interaction corrected local spin density...
High-Pressure Structures of Ge above 100 GPa (2001)
Takemura,K., Schwarz,U., Syassen,K., Christensen,N. E., Hanfland,M., Novikov,D. L., ...
High-pressure structures of Ge above 100 GPa (2001)
Takemura, K., Schwarz, U., Syassen, K., Christensen, N. E., Hanfland, M., Novikov, D. L., ...
High-Pressure Structures of Ge above 100 GPa (2001)
Takemura, K., Schwarz, U., Syassen, K., Christensen, N. E., Hanfland, M., Novikov, D. L., ...
Electronic structure and ferroelectricity in SrBi2Ta2O9 (2000)
Stachiotti, M. G., Rodriguez, C. O., Ambrosch-Draxl, C., Christensen, N. E.
The electronic structure of SrBi2Ta2O9 is investigated from first-principles, within the local density approximation, using the full-potential linearized augmented plane wave (LAPW) method. The...
Ab initio thermodynamics of body-centred cubic and face-centred cubic Cs (2000)
Christensen, N.E., Boers, D.J., Velsen, J.L. Van, Novikov, D.L.
Ab initio thermodynamics of bcc- and fcc cesium (2000)
Christensen, N.E., Novikov, D.L., Boers, D.J., Velsen, J.L. Van
Negative thermal expansion coefficient and isostructural transition in fcc cesium (2000)
Christensen, N.E., Boers, D.J., Velsen, J.L. Van, Novikov, D.L.
Ab initio thermodynamics of bcc- and fcc cesium (2000)
Christensen, N.E., Novikov, D.L., Boers, D.J., Velsen, J.L. Van
New high-pressure phases of lithium (2000)
Hanfland, M., Syassen, K., Christensen, N. E., Novikov, D. L.
Phase stability of highly compressed cesium (2000)
Takemura, K., Christensen, N. E., Novikov, D. L., Syassen, K., Schwarz, U., Hanfland, M.
High-pressure Cmca and hcp phases of germanium (2000)
Takemura, K., Schwarz, U., Syassen, K., Hanfland, M., Christensen, N. E., Novikov, D. L., ...
First-principles and semi-empirical calculations for bound hole polarons in KNbO3 (1999)
Kotomin, E. A., Eglitis, R. I., Postnikov, A. V., Borstel, G., Christensen, N. E.
The ab initio linear muffin-tin-orbital (LMTO) formalism and the semi-empirical method of the Intermediate Neglect of the Differential Overlap (INDO) based on the Hartree-Fock formalism are combined...
Computer simulations of defects in perovskite KNbO3 crystals (1998)
Eglitis, R. I., Kotomin, E. A., Postnikov, A. V., Christensen, N. E., Korotin, M. A., Borstel, G.
An ab initio LMTO approach and semi-empirical quantum chemical INDO method have been used for supercell calculations of basic point defects - F-type centers and hole polarons bound to cation vacancy...
Applications of the generalized gradient approximation to ferroelectric perovskites (1998)
Tinte, S., Stachiotti, M. G., Rodriguez, C. O., Novikov, D. L., Christensen, N. E.
The Perdew-Burke-Ernzerhof generalized gradient approximation to the density functional theory is tested with respect to sensitivity to the choice of the value of the parameter $\kappa$, which is...
Eglitis, R. I., Kotomin, E. A., Postnikov, A. V., Christensen, N. E., Borstel, G.
The LMTO method based on the density-functional theory and the semi-empirical INDO method based on the Hartree--Fock formalism are used for the supercell study of the F centers in cubic and...
First-principles and semiempirical calculations for F centers in KNbO3 (1997)
Eglitis, R. I., Christensen, N. E., Kotomin, E. A., Postnikov, A. V., Borstel, G.
The linear muffin-tin-orbital method combined with density functional theory (local approximation) and the semiempirical method of the intermediate neglect of the differential overlap (INDO) based on...
Calculated defect levels in GaN and AlN and their pressure coefficients. (1997)
Gorczyca Svane, I. Gorczyca, A. Svane, N. E. Christensen
Using the Green's function technique based on the linear muffin-tin orbital method in the atomic-spheres approximation we perform self-consistent calculations of the electronic structure of...
Electric-field gradient at the Fe nucleus in e-FeSi (1996)
Fanciulli, M., Zenkevich, A., Wenneker, I., Svane, A., Christensen, N.E., Weyer, G.
Confinement and the CLOPW method (1996)
Bekker, H.G., Wijers, C.M.J., Christensen, N.E.
Plane waves and Confined Localized Orbitals have been used to construct a new mixed basis for electronic structure calculations. Confinement is a mathematical transformation which smoothly suppresses...
Confinement and the CLOPW method (1996)
Bekker, Dr.ir. H.G., Wijers, Dr. C.M.J., Christensen, N.E.
Plane waves and Confined Localized Orbitals have been used to construct a new mixed basis for electronic structure calculations. Confinement is a mathematical transformation which smoothly suppresses...
Confinement and the CLOPW method (1996)
Bekker, H.G., Wijers, C.M.J., Christensen, N.E.
Plane waves and Confined Localized Orbitals have been used to construct a new mixed basis for electronic structure calculations. Confinement is a mathematical transformation which smoothly suppresses...