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The finite field approach has been implemented in the periodic ab initio CRYSTAL program and been used for calculating the dielectric constants of crystalline LiF and MgO (FCC structure) and BeO (wurtzite structure). To maintain the periodicity along the applied field direction, a "sawtooth" potential is used in conjunction with a supercell scheme. Supercells four to five times longer than the primitive cell in the direction of the applied field provide well-converged results. The influence of the computational parameters is discussed. An alternative scheme has also been implemented, for inner check, that consists of applying a static electric field to a slab of increasing thickness in the direction orthogonal to the surface; the dielectric response at the center of the slab is shown to converge rapidly to the bulk value evaluated with the sawtooth field. The method is accurate and permits the determination of nonlinear corrections to the dielectric constant. When used in conjunction with the local density approximation (LDA) scheme, it provides for the dielectric constant of the three above-mentioned compounds values close to those recently obtained with a time-dependent density functional theory approach. 相似文献
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Martinez-Casado R Mallia G Harrison NM 《Chemical communications (Cambridge, England)》2011,47(15):4385-4387
A practical and efficient method for exploiting second order Rayleigh-Schr?dinger perturbation theory to approximate the correlation energy contribution to the London dispersion interaction is presented. The correlation energy is estimated as the M?ller-Plesset contribution computed using single particle orbitals from hybrid exchange density functional theory as the reference state. 相似文献
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H. Mühe Mc. Candless E. Valenta Utz Wilh Vaubel B. Ahlström O. Aschan J. Kondakow J. Schindelmeiser R. Böhme H. Herzfeld J. E. Teeple R. Adan J. Marcusson Darmois H. Wolff C. Piest R. Marcille EA. Parry M. Adams H. W. Fosse K. Ihnatowzcz 《Analytical and bioanalytical chemistry》1917,56(10-11):541-560
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RD Harris WS Baker Van Stipdonk MJ RM Crooks EA Schweikert 《Rapid communications in mass spectrometry : RCM》1999,13(14):1374-1380
A suite of keV polyatomic or 'cluster' projectiles was used to bombard unoxidized and oxidized self-assembled monolayer surfaces. Negative secondary ion yields, collected at the limit of single ion impacts, were measured and compared for both molecular and fragment ions. In contrast to targets that are orders of magnitude thicker than the penetration range of the primary ions, secondary ion yields from polyatomic projectile impacts on self-assembled monolayers show little to no enhancement when compared with monatomic projectiles at the same velocity. This unusual trend is most likely due to the structural arrangement and bonding characteristics of the monolayer molecules with the Au(111). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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The adsorption of vinyl fluoride on the rutile TiO2(1 1 0) surface has been simulated, on the basis of a recently proposed experimental model, using hybrid-exchange density functional theory. Different surface coverages have been considered and the lateral interaction between adsorbed vinyl fluoride molecules has been quantified through a simple model of nearest and next nearest neighbouring molecules. The vibrational frequencies of the adsorbed molecule have been calculated and are found to be in excellent agreement with those observed providing support for the proposed adsorption model. The effect of the adsorption on the electronic structure of the molecule and the surface have been characterised by computing electrostatic potential maps and the local density of states. 相似文献
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Aderholz M Aggarwal MM Akbari H Allport PP Badyal SK Ballagh HC Barth M Baton JP Bingham HH Brucker EB Burnstein RA Campbell JR Cence RJ Chatterjee TK Clayton EF Corrigan G Coutures C DeProspo D Devanand De Wolf EA Faulkner PJ Foeth H Fretter WB Gupta VK Hanlon J Harigel G Harris FA Jabiol MA Jacques P Jain V Jones GT Jones MD Kafka T Kalelkar M Kasper P Kohli JM Koller EL Krawiec RJ Lauko M Lys JE Marage P Milburn RH Miller DB Mittra IS Mobayyen MM Moreels J Morrison DR Myatt G Nailor P 《Physical review D: Particles and fields》1992,45(7):2232-2243