Dear all,<br> I want to know the atomic displacement and vibrational amplitude under different pressures in alloys, for example AB3. At the gamma point, the file AB3.dynG contains the calculated results, part of the acoustic branches are shown as following, and I know from the mailing list that after the omega line is the eigendisplacement of each atom.
<br><br>**********************************AB3.dynG*********************<br>.............<br> omega( 1) = 1.321104 [THz] = 44.067563 [cm-1]<br> ( 0.054100 0.000000 0.104646 0.000000 -0.485673 0.000000 )
<br> ( 0.054107 0.000000 0.104658 0.000000 -0.486512 0.000000 )<br> ( 0.054107 0.000000 0.104827 0.000000 -0.485728 0.000000 )<br> ( 0.054194 0.000000 0.104658 0.000000 -0.485728 0.000000 )<br> omega( 2) =
1.321104 [THz] = 44.067563 [cm-1]<br> ( -0.230668 0.000000 -0.427404 0.000000 -0.117786 0.000000 )<br> ( -0.230694 0.000000 -0.427453 0.000000 -0.117990 0.000000 )<br> ( -0.230694 0.000000 -0.428142 0.000000 -
0.117800 0.000000 )<br> ( -0.231067 0.000000 -0.427453 0.000000 -0.117800 0.000000 )<br> omega( 3) = 1.321104 [THz] = 44.067563 [cm-1]<br> ( -0.440024 0.000000 0.236919 0.000000 0.002033 0.000000 )
<br> ( -0.440074 0.000000 0.236946 0.000000 0.002036 0.000000 )<br> ( -0.440074 0.000000 0.237328 0.000000 0.002033 0.000000 )<br> ( -0.440784 0.000000 0.236946 0.000000 0.002033 0.000000 )<br>........<br>************************************************************************************
<br>While when we perform Fourier transformation with q2r.x, we can get the interatomic force constants in real space. Then with program matdyn.x, we can recalculate phonon modes at any q. The results of acoustic branches at gamma point, are also shown as following (with the acoustic sum rule applied):
<br><br>*****************************matdyn.modes***********************<br>.......................<br> omega( 1) = 0.000000 [THz] = -0.000013 [cm-1]<br> ( -0.008792 0.000000 0.001394 0.000000 0.499921
0.000000 )<br> ( -0.008792 0.000000 0.001394 0.000000 0.499921 0.000000 )<br> ( -0.008792 0.000000 0.001394 0.000000 0.499921 0.000000 )<br> ( -0.008792 0.000000 0.001394 0.000000
0.499921 0.000000 )<br> omega( 2) = 0.000000 [THz] = 0.000016 [cm-1]<br> ( -0.027902 0.000000 0.499217 0.000000 -0.001883 0.000000 )<br> ( -0.027902 0.000000 0.499217 0.000000
-0.001883 0.000000 )<br> ( -0.027902 0.000000 0.499217 0.000000 -0.001883 0.000000 )<br> ( -0.027902 0.000000 0.499217 0.000000 -0.001883 0.000000 )<br> omega( 3) = 0.000001
[THz] = 0.000023 [cm-1]<br> ( -0.499143 0.000000 -0.027930 0.000000 -0.008701 0.000000 )<br> ( -0.499143 0.000000 -0.027930 0.000000 -0.008701 0.000000 )<br> ( -0.499143 0.000000 -0.027930
0.000000 -0.008701 0.000000 )<br> ( -0.499143 0.000000 -0.027930 0.000000 -0.008701 0.000000 )<br>***************************************************************************************<br><br>My question is that between these two results of eigendisplacement, why they are so much different and which one is reasonable. Beside, another question is that, could I square these eigendisplacement, respectively and plus them together to obtain the vibrational amplitude (that is, SQRT[x^2 + y^2 + z^2] ) .
<br><br>Thanks in advance!<br><br>Sincerely<br><br>Kong<br><br>-- <br>=============================<br>Yi Kong<br>Building 23, Room 240<br>Department of MS&E<br>Tsinghua University<br>PR China, 100084<br><br>Phone:86-10-6278-1255
<br>Fax: 86-10-6278-1255<br>Email: <a href="mailto:kongy03@mails.tsinghua.edu.cn">kongy03@mails.tsinghua.edu.cn</a><br>or <a href="mailto:yi.kong@gmail.com">yi.kong@gmail.com</a><br>=============================