User notes for vasp laboratory computing resource center. The vasp manual recommends that you set prec to high, and that encut be set to. The number of kpoints necessary for a calculation depends critically on the necessary precision and on the fact whether the system is metallic. What is the kpoints in electronic structure calculations. New features and releases, bugfixes, highlighted papers, and more.
The number of kpoints in the returned grid will scale roughly as mindistance d, where d is the number of periodic dimension e. In the kpoints file you specify the points vasp will use to sample the first brillouin zone in reciprocal space. I do this by varying the k points number n x n x 1 and getting the energy. Vasp computational materials physics universitat wien. Brillouin zone integration vasp aflow aconvasp abstract the article is devoted to the discussion of the highthroughput approach to band structures calculations. To get the best performance, we recommend you select a value of mindistance carefully. Use reciprocal units if kpoints are specified explicitly. The above file instructs vasp to calculate the energy at each k point between gamma point and x point, gamma point and l point. Widom computer physics communications 183 2012 14221426 table 1 parametersfortypicalruns. If the second line equals zero, kpoints are generated automatically using the monkhorst. A pre and postprocessing program for the vasp code. In energy and relaxation calculations, i do a convergence test to determine the best number of k points.
L by specifying the linemode, vasp automatically interpolate between the points you. Introducing kpoint parallelism into vasp sciencedirect. Everybody is welcome to have a look, but posting questions and answers is reserved for licensed user only. Potcar file is provided by vasp then run vasp after job is completed, we get charge density in chgcar file to get band structure, run nonself consistence calculation for each desired k points. Vmware, virtualbox phonopy requires force calculators, e. By specifying the linemode, vasp automatically interpolate between the points you want to calculate. There are three vasp binaries for each architecture vaspgam gammapoint only, vaspstd multiple kpoints and vaspncl noncollinear spins. In vasp, how do we determine the best number of k points for dos.
The latter calculation was performed over 360 processors on the hector phase 2b system, with a speedup factor of approximately compared to the standard version running on 24 processors ideal. In general, you only need many kpoints in relatively small cells, so up front we would expect kpoint parallelization to improve timetosolution for small cells with hundreds or thousands of kpoints. The goal of this script is to run vasp in iterations with different lattice constants. A bit of surface science university of vienna, faculty of physics and center for computational materials science. Pdf introducing kpoint parallelism into vasp researchgate. Software codes here is a list of software codes that may be used to perform the sort of research of interest to the psik community. The number of k points necessary for a calculation depends critically on the necessary precision and on the fact whether the system is metallic. Pdf for many years ab initio electronic structure calculations based upon density functional theory have been one of the main application areas in. The electronic wave functions at k points that are very close together will be almost identical, hence it is possible to represent the electronic wave functions over a region of k space by the wave functions at a single k point. In solidstate theory k space is often used to mean reciprocalspace in general, but in electronicstructure theory k points have a much more specific meaning.
Use of symmetries allows treatment of only symmetry inequivalent k points and reduces computation. Kpar cores time s speedup 1 64 293 64 2 128 159 118. Define the points vasp uses to sample the first brillouin zone in reciprocal space. Is there a systematic method similar above in order to determine the best number of k points for dos calculations. After the run, copy the ibzkpt file to the kpoints file this file stores explictly the list of kpoints used in the previous calculation, and simply add the desired additional kpoints with zero weight. In vasp, how do we determine the best number of k points. The kpoints sampling along this smaller brillouin zone should be chosen as a subset of the kpoint mesh in the larger brillouin zone, such that the position of the kpoints in this subset, expressed in cartesian coordinates in reciprocal space, agree in both calculations to check whether this is actually the case, inspect the list of kpoints. If the second line equals zero, k points are generated automatically using the monkhorstpacks technique first character in third line equals m.
After starting vasp, you will get a output similar to. Testing the kpoint parallelization in vasp peter larsson. Nkptisthenum ber of symmetryindependent kpoints, and ngx the linear dimension of the fft grid. Phonopy is a phonon calculation toolbox and toolkit easily installed on ubuntu or recent distributions currently windows and mac os x are out of consideration. A portable, multiplatform, commandline driven graphing utility. In solidstate theory kspace is often used to mean reciprocalspace in general, but in electronicstructure theory kpoints have a much more specific meaning. Windows and mac users are encouraged to boot ubuntu on a virtual machine e.
I have applied a patch so a clearer exception is now raised when this happens. What can we expect from this new feature in terms of performance. Number of kpoints, and method for smearing read and understand section 7. Net charge per unit cell as an alternative to specifying the total charge nelect. Kpoints automatic generation mp scheme 0 monkhorstpack 8 8 6 0 0 0 define the path of kpoints along which band structures are calculated. Links to home pages are given where possible, together with a short description and some details about licensing. Since vasp uses an iterative matrix diagonalization and since the added kpoints do not influence the energy, one needs to force vasp to.