<html><body><div style="color:; background-color:; font-family:MS PGothic, sans-serif;font-size:12pt"><div style="font-family: 'MS PGothic', sans-serif; font-size: 12pt;">Dear all,</div><div style="font-family: 'MS PGothic', sans-serif; font-size: 12pt;"><br></div><div><font face="MS PGothic, sans-serif">It is begun these days to use QE and DFPT is studied. </font><br></div><div><font face="MS PGothic, sans-serif">There is an easy question. <br></font></div><div><font face="MS PGothic, sans-serif">Electron density(n(r)) is made from the plane wave set in this code? <br></font></div><div><font face="MS PGothic, sans-serif">A plane wave cannot be dependent on nuclear coordinates.(exp(ikr))<br></font></div><div><font face="MS PGothic, sans-serif">In DFPT, the differentiation in the nuclear coordinates of electron density is required. <br></font></div><div><font face="MS PGothic, sans-serif"><div>I will think that the differentiation in
the nuclear coordinates of electron density will disappear. </div><div><div>If surely a nucleus changes, density is also likely to change. </div><div>However, a base is a plane wave. </div><div>It is not dependent on a nuclear position.</div></div><div><br></div><div>sum of plane wave set (sigma {exp(ikr)}) → density n(r) → dn(r)/dR is vanish ... ???</div><div><br></div><div>Where do I mistake? <br></div><div>please help me.</div><div><br></div><div><br></div><div>Best,</div><div>Tomson</div></font></div></div></body></html>