Hi, Happy new year ~!<br><br><br><div class="gmail_quote">On Jan 6, 2008 10:10 AM, Faridul Isalm <<a href="mailto:faridul@email.com">faridul@email.com</a>> wrote:<br><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
Dear Sir,<br>I am a novice user of Quantum Espersso (PWscf).I use it on the CYGWIN platform. I did the examples successfully those are given with Quantum Espresso package. I am now trying to learn "band structure calculation" step. But I face the following problems:
<br><br>1) when I run plotband.x, there need to specify "Efermi", but where I get this value. I look all output files, nowhere that is. such as for Si Efermi = 6.337, from where this value comes.<br></blockquote>
<div> you can find fermi level at output, if not, i think it is due to your smearing scheme of the calculation. For semiconductor, the fermi level should be at the middle of bandgap. For metal<br>system, i think pwscf should always be able to give you the value of fermi level in you output file.
<br> <br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>2)when this method is used for other materials such as SiO2, MnO2, GaAs, etc., then how can i specify their ibrav in the &system namelist. and also how can I know their celldm.
</blockquote><div> i think you should read the last part of INPUT_PW.. it gives you detail description of crystal<br>system building. of coz, you should know the coordinates of these systems before you starting to handle .. you may obtain coordinates from this
<a href="http://cst-www.nrl.navy.mil/lattice/">http://cst-www.nrl.navy.mil/lattice/</a> .<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">
<br><br>3)when it is used for semiconductor materials, then which variables may need to specify in the &system namelist.<br></blockquote><div> there are several examples for semiconductors in $QE/examples, i think you can benefit from these tests.
<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>4)how can I determine the proper "ecutwfc" of a particular material. is it =kT?
</blockquote><div> <br>hmmm, ecutwfc is one of the most key parameters in periodic boundary calculation,<br> which determines your calculation's accuracy. it should not be equal to kT, i think it is too<br>
small to believe. why not to read again INPUT_PW ?<br><br></div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br><br>5)I face a great problem when I use k-points {automatic}, then output of the band does not match with the given examples. But when I use 36 k-points that are given in the examples then it is ok. Now how can I choose the proper k-points for a particular material.
<br></blockquote><div><br> for this problem, i think you should figure out 2 different calculations , scf and nscf, for scf calculation , we use kpoint to sample BZ to obtain convergent electron density , for nscf calculation , we use k-point path to obtain bandstructure and other quantities . k-point path
<br>is the reciprocal path between high symmetry points of your sytem.<br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>6)When I run xcrysden --pwo
si.scf.out, then i get " the hardware does not support the stereo" error massage. My computer is "Intel Core2 Duo, 1.86GHz, 512MB RAM". how can i solve this problem.<br></blockquote><div>while, this problem should be due to your video card, or your improper installing related driver
<br>program of video card<br><br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br>I will be very greatful to you, if you kindly give me the solutions of the above mentioned problems. I want to learn about this method clearly. I will be very happy if you give me yours further valuable successions that can help me to learn.
</blockquote><div><br><br> </div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"><br><br>I am looking forward to hearing from you.<br>Thank you for your valuable time.
<br><br>Sincerely<br>Dr. <a href="http://A.K.Md" target="_blank">A.K.Md</a> Farid ul Islam<br>Assistant Professor,<br>Dept. of Physics,<br>Carmichael University College, Rangpur-5004, Bangladesh<br><font color="#888888"><br>
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<br></font></blockquote></div><br><br>bests, hai-ping<br clear="all"><br>-- <br>Hai-Ping Lan <br>Department of Electronics ,<br>Peking University , Bejing, 100871<br><a href="mailto:lanhaiping@gmail.com">lanhaiping@gmail.com
</a>, <a href="mailto:hplan@pku.edu.cn">hplan@pku.edu.cn</a>