1 / 19

Javier Junquera

Exercises on basis set generation Control of the range of the second- ς orbital: the split norm . Javier Junquera. Most important reference followed in this lecture. Default mechanism to generate multiple-  in SIESTA: “ Split-valence ” method.

ledell
Download Presentation

Javier Junquera

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Exercises on basis set generation Control of the range of the second-ς orbital: the split norm Javier Junquera

  2. Most important reference followed in this lecture

  3. Default mechanism to generate multiple- in SIESTA: “Split-valence” method Starting from the function we want to suplement

  4. Default mechanism to generate multiple- in SIESTA: “Split-valence” method The second- function reproduces the tail of the of the first- outside a radius rm

  5. Default mechanism to generate multiple- in SIESTA: “Split-valence” method And continuous smoothly towards the origin as (two parameters: the second- and its first derivative continuous at rm

  6. Default mechanism to generate multiple- in SIESTA: “Split-valence” method The same Hilbert space can be expanded if we use the difference, with the advantage that now the second- vanishes at rm (more efficient)

  7. Default mechanism to generate multiple- in SIESTA: “Split-valence” method Finally, the second- is normalized rm controlled with PAO.SplitNorm

  8. Meaning of the PAO.SplitNorm parameter PAO.SplitNormistheamount of thenorm (the full normtail + parabollanorm) thatthesecond-ς split off orbital has to carry (typical value 0.15)

  9. Bulk Al, a metal that crystallizes in the fcc structure As starting point, we assume the theoretical lattice constant of bulk Al FCC lattice Sampling in k in the first Brillouin zone to achieve self-consistency Go to the directory with the exercise on the energy-shift More information at the Siesta web page http://www.icmab.es/siesta and follow the link Documentations, Manual Inspect the input file, Al.energy-shift.fdf

  10. For each basis set, a relaxation of the unit cell is performed Variables to control the Conjugate Gradient minimization Two constraints in the minimization: - the position of the atom in the unit cell (fixed at the origin) - the shear stresses are nullified to fix the angles between the unit cell lattice vectors to 60°, typical of a fcc lattice

  11. The splitnorm: Variables to control the range of the second-ς shells in the basis set

  12. The splitnorm: Run Siesta for different values of the PAO.SplitNorm Then, runSiesta Editthe input file and set up PAO.SplitNorm 0.10 $siesta < Al.splitnorm.fdf > Al.splitnorm.0.10.out

  13. For each splitnorm, search for the range of the orbitals Editeach output file and searchfor:

  14. For each splitnorm, search for the range of the orbitals Editeach output file and searchfor: We are interested in thisnumber

  15. For each splitnorm, search for the range of the orbitals Editeach output file and searchfor: Thelatticeconstant in this particular case would be 2.037521 Å × 2 = 4.075042 Å

  16. For each energy shift, search for the timer per SCF step We are interested in thisnumber

  17. The SplitNorm: Run Siesta for different values of the PAO.SplitNorm Then, runSiesta Editthe input file and set up PAO.SplitNorm 0.15 $siesta < Al.splitnorm.fdf> Al.splitnorm.0.15.out Try different values of the PAO.EnergyShift PAO.SplitNorm 0.10 $siesta < Al.splitnorm.fdf> Al.splitnorm.0.10.out PAO.SplitNorm 0.20 $siesta < Al.splitnorm.fdf> Al.splitnorm.0.20.out PAO.SplitNorm 0.25 $siesta < Al.splitnorm.fdf> Al.splitnorm.0.25.out PAO.SplitNorm 0.30 $siesta < Al.splitnorm.fdf> Al.splitnorm.0.30.out

  18. Analyzing the results Edit in a file (called, for instance, splitnorm.dat) the previous values as a function of the SplitNorm

  19. Analyzing the results: range of the orbitals as a function of the split norm $ gnuplot $ gnuplot> plot”splitnorm.dat" u 1:2 w l, ”splitnorm.dat" u 1:3 w l $ gnuplot> set terminal postscript color $ gnuplot> set output “range-2zeta.ps” $ gnuplot> replot ThelargertheSplitNorm, thesmallertheorbitals

More Related