<html><head></head><body><div class="ydp2d2e02afyahoo-style-wrap" style="font-family:Helvetica Neue, Helvetica, Arial, sans-serif;font-size:16px;"><div dir="ltr" data-setdir="false">Dear Dr. Timrov,</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">Thanks for your answer. </div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I was trying to perform the calculation with Si as a test.. Now I'm trying to perform the calculation with the crystal I'll work with... I want to reproduce the paper "DFT calculations of the structural, electronic, optical and vibrational properties of anhydrous orthorhombic L-threonine crystals" but with another amino acid (4 molecules in the crystal). My first question is, in this situation, should I create a supercell?</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false">I applied the same parameters in the SCF (gamma k-points), Lanczos, and Spectrum. In the end, I got the plot_S and plot_chi files. In the former, it has the column omega(Ev) and Oscillator strength. In the second, there's a kind of matrix:</div><div dir="ltr" data-setdir="false"><div><div> \hbar \omega(eV) Re(chi) (e^2*a_0^2/eV) Im(chi) (e^2*a_0^2/eV)</div><div> chi_1_1= 0.000000000000000E+00 0.251513541607848E+02 -.000000000000000E+00</div><div> chi_2_1= 0.000000000000000E+00 0.289682796308743E-01 -.000000000000000E+00</div><div> chi_3_1= 0.000000000000000E+00 -.627424728613613E+01 0.000000000000000E+00</div><div> chi_1_2= 0.000000000000000E+00 0.287160382756907E-01 -.000000000000000E+00</div><div> chi_2_2= 0.000000000000000E+00 0.316761800714172E+02 -.000000000000000E+00</div><div> chi_3_2= 0.000000000000000E+00 -.136008122822626E-01 0.000000000000000E+00</div><div> chi_1_3= 0.000000000000000E+00 -.627868400613771E+01 0.000000000000000E+00</div><div> chi_2_3= 0.000000000000000E+00 -.132116766101710E-01 0.000000000000000E+00</div><div> chi_3_3= 0.000000000000000E+00 0.250771241870414E+02 -.000000000000000E+00</div><div><br></div><div dir="ltr" data-setdir="false">I believe the Real and Imaginary parts of the Dielectric function are columns 3 and 4. How can I use these data to plot a graph for the different directions ([001] [010][100])?</div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"> </div></div></div><div dir="ltr" data-setdir="false"><br></div><div dir="ltr" data-setdir="false"><br></div></div></body></html>