<html>
<head>
<style><!--
.hmmessage P
{
margin:0px;
padding:0px
}
body.hmmessage
{
font-size: 10pt;
font-family:΢ÈíÑźÚ
}
--></style>
</head>
<body class='hmmessage'>
<br><br><br>Dear Paolo, <br><br>The re-generated phonon from the force constant matrix are negative. <br> 0.177215 0.000000 0.000000<br> -45.4648 -45.4648 119.2232 626.1196 626.1196 645.7030<br><br>comparing to the frequency got by ph.x <br><br> q = ( 0.177215000 0.000000000 0.000000000 ) <br><br> **************************************************************************<br> omega( 1) = 0.431524 [THz] = 14.394177 [cm-1]<br> ( 0.000000 0.000000 0.129619 -0.022092 0.597312 -0.371775 ) <br> ( 0.000000 0.000000 0.118762 0.048530 0.686479 0.000000 ) <br> omega( 2) = 0.431524 [THz] = 14.394177 [cm-1]<br> ( -0.000000 0.000000 -0.693560 0.118207 0.111631 -0.069481 ) <br> ( -0.000000 -0.000000 -0.635471 -0.259673 0.128295 -0.000000 ) <br> omega( 3) = 3.535384 [THz] = 117.928499 [cm-1]<br> ( -0.661130 -0.445106 0.000000 0.000000 0.000000 -0.000000 ) <br> ( -0.247111 -0.551111 0.000000 0.000000 0.000000 0.000000 ) <br> omega( 4) = 18.715499 [THz] = 624.285984 [cm-1]<br> ( -0.000000 -0.000000 0.000000 -0.000000 -0.106238 0.066124 ) <br> ( 0.000000 0.000000 -0.000000 -0.000000 0.992140 0.000000 ) <br> omega( 5) = 18.715499 [THz] = 624.285984 [cm-1]<br> ( -0.000000 -0.000000 -0.110727 0.058294 0.000000 -0.000000 ) <br> ( 0.000000 0.000000 0.989559 0.071511 0.000000 -0.000000 ) <br> omega( 6) = 19.507679 [THz] = 650.710441 [cm-1]<br> ( 0.080574 0.054886 -0.000000 -0.000000 -0.000000 -0.000000 ) <br> ( -0.402244 -0.910327 0.000000 0.000000 0.000000 0.000000 ) <br> **************************************************************************<br><br>Maybe something wrong in the generation of interatomic force constant, but how to check it? Thanks a lot.<br><br>Sincerely,<br>Pan Hao <br>Tulane University <br>
<meta http-equiv="Content-Type" content="text/html; charset=unicode">
<meta name="Generator" content="Microsoft SafeHTML">
<style>
.ExternalClass .ecxhmmessage P
{padding:0px;}
.ExternalClass body.ecxhmmessage
{font-size:10pt;font-family:΢ÈíÑźÚ;}
</style>
<pre> <br>Quoting HaoPan <<a href="http://www.democritos.it/mailman/listinfo/pw_forum" target="_blank">adehaopan at hotmail.com</a>>:<br><br>><i> On each q point I got, the phone frequencies are positive. But after <br></i>><i> the Fourier interpolation process, There exist negative frequencies.<br></i><br>hard to say what is happening. When you re-generate phonon from<br>the force constant matrix, you should find exactly the same phonon<br>frequencies for the wave-vector grid used to generate force constants<br>in real space. If not, something has gone wrong in the generation<br>of interatomic force constants<br><br>Paolo<br><i><a href="http://www.democritos.it/mailman/listinfo/pw_forum" target="_blank"></a></i></pre> </body>
</html>