ABINIT Discussion Forums

Hello erverybody,
First I must admit that I am a newcomer for abinit software. a problem always trouble me recently. I want to know the difference between the optimization in files in Tutorial 3 and that in "elastic" lesson of the tutorial.
I want calculate the elastic tensor and piezoelastic tensor and dialectic tensor by the response function method. As we know, input variables xred should be optimized through variables iafix and nafix. But it is so hard to set thses two variables for a complicated crystal. As a result, I plan to use the result from the former method introduced. by Tutorial 3.
So is it right or wrong for my thought.？ Thanks, wait for your reply!
Best wishes!

In my rf in files, I introduce the acell， rprim and xred from the result
As follows,
acell 9.3098350644E+00 9.3098350644E+00 9.3098350644E+00
rprim 7.7865721261E-01 4.4955795131E-01 4.3771062778E-01
-7.7865721261E-01 4.4955795131E-01 4.3771062778E-01
-2.2038932035E-16 -8.9911590261E-01 4.3771062778E-01
xred 5.3990052785E-01 1.6033867550E-01 5.3990052785E-01
-5.7533165555E-03 -5.7533165555E-03 -5.7533165555E-03
2.4162683852E-01 2.4162683852E-01 2.4162683852E-01
3.9092544714E-01 7.7296920180E-01 3.9092544714E-01
8.2492988771E-01 1.5476687533E-01 8.2492988771E-01
1.6033867550E-01 5.3990052785E-01 5.3990052785E-01
7.7296920180E-01 3.9092544714E-01 3.9092544714E-01
1.5476687533E-01 8.2492988771E-01 8.2492988771E-01
5.3990052785E-01 5.3990052785E-01 1.6033867550E-01
3.9092544714E-01 3.9092544714E-01 7.7296920180E-01
8.2492988771E-01 8.2492988771E-01 1.5476687533E-01

Hi!

This may not be what you're asking for, but could be important.
By looking at your outputted xred's, it seems that none of your atoms have their coordinates fixed by symmetry. Therefore, you should not use iatfix and natfix in the optimization. If any of your atoms don't have fixed coordinates and you fix them in your input file (using iatfix and natfix), abitnit won't optimize them, and you will end up with unrelaxed structure.

Igor L.

Thanks a lot! Your reply is so useful!
thanks again!

nannan