<div dir="ltr"><div>Dear all,</div><div><br></div><div>I am trying to calculate the
phonon dispersion for Silicon. Thanks to the previous posts, I think I
understand the structure of the output file and how to extract the
interatomic force constant matrices.</div><div> Since the Cartesian
frame is given by the vectors (-1,0,1)a/2; (0,1,1)a/2 and (-1,1,0)a/2,
where can I find the IFC for the interaction between the two atoms in
the unit cell, namely the interaction between atom at (0,0,0) and the 4
nearest neighbors at (1/4,1/4,1/4), (1/4,-1/4,-1/4), (-1/4,1/4,-1/4),
(-1/4,-1/4,1/4)? I would expect to find it in the section 1 1 1 2
section but none of the position vector match the four first nearest
neighbor, unless I making a mistake:</div><div><br></div><div>1 1 1 2<br> 1 1 1 -6.76355682813E-02<br> 2 1 1 7.83560937500E-05<br> 3 1 1 -4.45195312500E-05<br> 4 1 1 7.20209843750E-04<br> 1 2 1 -6.76355682813E-02<br> 2 2 1 -4.13570781250E-04<br> 3 2 1 -4.13570781250E-04<br> 4 2 1 -6.76355682813E-02<br> 1 3 1 -4.63088953125E-03<br> 2 3 1 1.34053593750E-04<br> 3 3 1 -4.13570781250E-04<br> 4 3 1 7.20209843750E-04<br> 1 4 1 -4.63088953125E-03<br> 2 4 1 -4.13570781250E-04<br> 3 4 1 -4.45195312500E-05<br> 4 4 1 3.78551718750E-04<br> 1 1 2 7.83560937500E-05<br> 2 1 2 1.17258593750E-04<br> 3 1 2 3.07267343750E-04<br> 4 1 2 7.20209843750E-04<br> 1 2 2 -4.13570781250E-04<br> 2 2 2 1.34053593750E-04<br> 3 2 2 -4.63088953125E-03<br> 4 2 2 7.20209843750E-04<br> 1 3 2 1.34053593750E-04<br> 2 3 2 1.34053593750E-04<br> 3 3 2 3.07267343750E-04<br> 4 3 2 3.07267343750E-04<br> 1 4 2 -4.13570781250E-04<br> 2 4 2 1.17258593750E-04<br> 3 4 2 2.44567968750E-04<br> 4 4 2 3.07267343750E-04<br> 1 1 3 -4.45195312500E-05<br> 2 1 3 3.07267343750E-04<br> 3 1 3 3.78551718750E-04<br> 4 1 3 2.42503593750E-04<br> 1 2 3 -4.13570781250E-04<br> 2 2 3 -4.63088953125E-03<br> 3 2 3 3.78551718750E-04<br> 4 2 3 -4.45195312500E-05<br> 1 3 3 -4.13570781250E-04<br> 2 3 3 3.07267343750E-04<br> 3 3 3 2.44567968750E-04<br> 4 3 3 1.17258593750E-04<br> 1 4 3 -4.45195312500E-05<br> 2 4 3 2.44567968750E-04<br> 3 4 3 2.44567968750E-04<br> 4 4 3 -4.45195312500E-05<br> 1 1 4 7.20209843750E-04<br> 2 1 4 7.20209843750E-04<br> 3 1 4 2.42503593750E-04<br> 4 1 4 2.42503593750E-04<br> 1 2 4 -6.76355682813E-02<br> 2 2 4 7.20209843750E-04<br> 3 2 4 -4.45195312500E-05<br> 4 2 4 7.83560937500E-05<br> 1 3 4 7.20209843750E-04<br> 2 3 4 3.07267343750E-04<br> 3 3 4 1.17258593750E-04<br> 4 3 4 7.83560937500E-05<br> 1 4 4 3.78551718750E-04<br> 2 4 4 3.07267343750E-04<br> 3 4 4 -4.45195312500E-05<br> 4 4 4 2.42503593750E-04</div><div><br></div><div>Thank you very much,</div><div><br></div><div>Best regards,</div><div>Adrien Descamps</div><div><br></div><div>Stanford Unversity, Aeronautics and Aerospace Engineering</div></div>