http://han.ess.sunysb.edu/EELS/#opennewwindow

This program calculates the Electron Energy Loss Spectrum (EELS)

To use this code, first use script "script_EELS" to generate input for this code.

To use in conjuction with USPEX - ONLY FOR VASP CODE

Remember to use this utility, user must specify few VASP tags in the INCAR file for the last stage of VASP calculations, such as:

    LOPTICS  = .TRUE.
    CSHIFT   =  0.01
    NEDOS    =  2000
    NOMEGA   =   100
    OMEGAMAX =    20
    OMEGATL  =   260

so that VASP can calculates imaginary and real parts of frequency dependent dielectric constant. The values of these variables should be choosen as per user's requirement. To know more about these tags refer to the VASP manual.

Once the OUTCAR from the last stage of VASP is obtained, one should run "./script_EELS" first and then upload OMEGA.dat, EPS_RE.dat and EPS_IM.dat files here to get the file having data which can be used to plot EELS correspoing to x, y and z-directions. The first column of the output file "LOSS_FN.txt" contains energies in eV, while 2nd, 3rd and 4th columns contain the data corresponding to EELS along x, y, and z-directions, respectively.

Note: One may need to edit the script if they change the value of NOMEGA and OMEGAMAX in INCAR file.

Should you have any question, feel free to contact Prof. Priya Johari.

Example: OMEGA.dat, EPS_RE.dat, EPS_IM.dat. 

Authors: Priya Johari (main code), Mahdi Davari, Maksim Rakitin (web interface)

Script_EELS:

grep -A2002  "IMAGINARY DIELECTRIC FUNCTION"  OUTCAR > 1
tail -2000  1 > EPS_IM.dat
grep -A2002  "REAL DIELECTRIC FUNCTION"   OUTCAR > 1
tail -2000  1 > EPS_RE.dat
grep "NOMEGA" INCAR > 2
sed 's/\(.\{7\}\)//'  2 > NOMEGA.dat
grep "OMEGAMAX" INCAR > 2
sed 's/\(.\{9\}\)//'  2 > OMEGAMAX.dat
cat NOMEGA.dat OMEGAMAX.dat > OMEGA.dat
rm -f NOMEGA.dat OMEGAMAX.dat