Density of States and Fermi Surface Calculations of Ni

Jump to: navigation, search

This example shows how to calculate the Density of States (DOS) and how to plot the Fermi Surface of Ni.

The calculation proceeds as follows (for the meaning of the cited input variables see the appropriate INPUT_* file)

  1. Make a self-consistent calculation (scf) for Ni (like in example 1).
    1. Input=ni.scf.in. Output=ni.scf.out.
    2. pw.x < ni.scf.in > ni.scf.out
  2. Make a band structure calculation for Ni (input=ni.dos.in, output=ni.dos.out) on a uniform k-point grid (automatically generated). In this example the Fermi level is calculated with the tetrahedra method (not in the actual band structure calculation but in the subsequent DOS calculation). If preferred, a gaussian broadening may be specified in this or in the subsequent step.
    1. Input=ni.band.in. Output=ni.band.out.
    2. pw.x < ni.band.in > ni.band.out
  1. the program dos.x reads file filpun (ni.pun) and calculates the DOS on a uniform grid of energies from Emin to Emax, with grid step Delta E. The output DOS is in file ni.dos, ready for plotting.
    1. pw.x < ni.dos.in > ni.dos.out
    2. dos.x < ni.dos2.in > ni.dos2.out
  2. The program projfwc.x projects the crystal wavefunctions on an orthogonalized basis set of atomic orbitals, calculates the Loewdin charges, spilling parameter, and the projected DOS (total DOS in file 'ni.pdos_tot', s and d component in files 'ni.pdos_atm#1(Ni)_wfc#1(s)' and 'ni.pdos_atm#1(Ni)_wfc#2(d)' respectively).  (input=ni.pdos.in, output=ni.pdos.in)
    1. projwfc.x < ni.kpdos.in > ni.kpdos.out
  3. The calculation of Fermi surface can be performed using code fs.x. The resulting file in .bxsf format can be read and plotted using XCrySDen. Fermi Surface plot (updated version of the tools by Eyvaz Isaev): make again a self-consistent calculation, followed by a non-scf calculation ('nscf') with tetrahedra (smearing is also OK as long as the Fermi energy s computed) and a dense automatic (Monkhorst-Pack) unshifted grid, using K_POINTS automatic 24 24 24 0 0 0 Finally, run the "fs.x" utility, specifying in namelist &fermi the correct "outdir" and "prefix", optionally the output filename "filfermi" and "DeltaE" (see below). The code will select bands that cross the Fermi energy Ef+/-1eV (or Ef+/-DeltaE if specified) and write them into file, "filfermi"_fs.bxsf for spin-unpolarized, "filfermi"_fsup.bxsf and "filfermi"_fsdw.bxsf for spin-polarized calculations (filfermi=prefix is not specified). Plot these files using "xcrysden --bxsf"

Results

JobT181-results-kpdos dw.png JobT181-results-kpdos up.png



Model New Results

Software Used

Quantum Espresso

QuantumEspressoLogo.jpg

Quantum ESPRESSO is an integrated suite of computer codes for electronic-structure calculations and materials modeling at the nanoscale. It is based on density-functional theory, plane waves, and pseudopotentials. Quantum ESPRESSO has evolved into a distribution of independent and inter-operable codes. The Quantum ESPRESSO distribution consists of a “historical” core set of components, and a set of plug-ins that perform more advanced tasks, plus a number of third-party packages designed to be inter-operable with the core components.


For more details see Quantum Espresso .

CloudShell

CloudShell.png


CloudShell allow users to access a bash shell on a terminal emulator or execute a bash shell script either on a cloud based single node high performance computing (HPC) server or on the master node of autoscaling HPC cluster started on Kogence platform.



CloudShell cannot be invoked on the compute nodes of the cluster. Although, CloudShell can be used to run a shell script on the master node of the cluster that in can turn send job to the compute nodes of the cluster. Please see the documentation of relevant software application/simulator/solver on Kogence (Software Library) for the details on how to use CloudShell to schedule jobs on the compute nodes of an autoscaling HPC cluster on Kogence platform.

Using CloudShell on Kogence

To see detailed step-by-step instructions on how to use CloudShell on Kogence free cloud supercomputing platform [click here]. First create or copy an existing Model (see Model Library) on Kogence. Select your cloud cluster hardware on the Cluster tab on the top NavBar. Create your own custom software applications stack by selecting desired software on the Stack tab on the top NavBar. You can search and select CloudShell if you need a shell terminal or if you need to run a shell script. From the dropdown menu, select a binary. CloudShell has 2 binaries:

  1. shell-terminal: On the empty textbox next the binary dropdown menu, type the name of the terminal emulator you want. Currently, Kogence supports following terminal emulators
    1. gnome-terminal: You can find more information here.
    2. xterm: You can find more information here
  2. bash-shell: On the empty textbox next the binary dropdown menu, type the name of your shell script. Make sure your shell script is available under the Files tab of your Model before you Run your Model.

For more details see CloudShell .