It starts from a single-crystal surface, serving as a model of a real catalytic particle, commonly by employing a slab model. 14.1 shows the general scheme for a DFT-based catalyst screening process.
![thomas fermi screening metal thomas fermi screening metal](https://slidetodoc.com/presentation_image/39a10a05ea4bbecc85f48453e2799360/image-14.jpg)
One of the promising developments is to add a fully nonlocal functional of the ground-state density to account for the vdW-DF nonlocal corrections, and a new family of “vdW” functionals, like vdW-DF and BEEF-vdW, have been developed.įig. Recently, many attempts have been done in order to account for the missing vdW dispersion between nonoverlapped densities, which is caused by the local nature of the GGA functional form. However, for extended surfaces, GGA-type functionals, for example, Perdew-Wang 1991 (PW91), Perdew-Burke-Ernzerhof (PBE), and revised-PBE functionals, are the most popular methods due to its low cost with satisfactory accuracy. By far, B3LYP is the most widely used functional for molecular systems. The last rung, random phase approximation (RPA), describes correlation energies from the unoccupied KS orbitals, and it is the only one that can possibly account for van der Waals (vdW) dispersion between nonoverlapped densities. The fourth rung, hyper-GGA, also referred as hybrid GGA, calculates exchange using a mixture of the exact exchange and a GGA exchange functional. The first rung, local spin-density approximation, uses only the local density as input, while the second and third levels, GGA and meta-GGA, respectively, include semilocal terms. The most popular density functional methods can be divided into five categories according to the fifth-rung “Jacob's ladder” presented by Perdew. Current routinely used computational methods are mainly based on the formulation of DFT addressed by Kohn and Sham (KS), where approximations are used for the exchange-correlation energy E XC, representing the entire unknown part of the energy functional. The modern DFT is based on two Hohenberg-Kohn theorems, which state that the ground-state electron density uniquely determines the potential and thus all properties of the system. However, its accuracy is limited by the errors due to the inaccurate representation of kinetic energy, exchange energy, and the complete neglect of electron correlation.
![thomas fermi screening metal thomas fermi screening metal](https://ars.els-cdn.com/content/image/1-s2.0-S0169433218315022-fx1.jpg)
![thomas fermi screening metal thomas fermi screening metal](https://i.ebayimg.com/images/g/uKAAAOSwIFNhMMzu/s-l1600.jpg)
In 1927, Thomas and Fermi independently developed the Thomas-Fermi model, which is the predecessor to modern DFT. But you may on occassion find the end of one day's lecture at the start of the file for the next day's lecture, so please look there if you think there might be something missing.Zhi-Jian Zhao, Jinlong Gong, in Studies in Surface Science and Catalysis, 2017 14.2 Background of DFT-Based Catalyst Screening The lecture note files correspond roughly to the material presented in a given day's lecture.
![thomas fermi screening metal thomas fermi screening metal](https://pubs.rsc.org/image/article/2017/FD/c6fd00256k/c6fd00256k-t1_hi-res.gif)
#Thomas fermi screening metal for free#
You can download Acrobat Reader for free here.
#Thomas fermi screening metal pdf#
The lectures are uploaded as pdf files, so you will need Adobe Acrobat Reader in order to read them. I hope, nevertheless that you will find them useful. I make no guarantees about their legibility, or that they are totally free of errors. Please be warned that these are the notes I prepare for myself to lecture from - they are not in general carefully prepared for others to read. My hand written class lecture notes are being scanned and uploaded for you to view.