On Tue, 10 May 2005, Prof.Dr. Kemal ÇOLAKOGLU wrote: | Dear A.Postnikov, | Many thanks for your suggestions on our problem.Firstly We have calculated | the lattice constant as 6.47 A (very cose to experiment , 6.48 A)for ground | state bulk properties.But we have set the input file more before as you | stated | MD.TargetPressure 0.5 GPa | MD.VariableCell T | to obtain the new equilibrium lattice constant for future work (Cij vs | P ).Our obtained lattice constants vs enegy | values are not expected ones as follows : | | lattice constant Energy | 6.0 -1454,395571 | 6.1 -1454,390932 | 6.2 -1454,397768 | 6.3 -1454,397499 | 6.4 -1454,398580 | 6.5 -1454,395873 | 6.6 - 1454,397538 | 6.7 -1454,398341 | 6.8 -1454,382220 | 6.9 -1454,385354 | As it can be seen , the data dont show the expected parabolic curve.So ,we | can not obtain new correct- lattice constant .What is the reason of this | discrepancy ? | Your hint will appreciated | Regards, | Kemal Colakoglu, | Gazi University, | Dept.of Phys.
Dear Kemal, your data show indeed a tendency to fall around a parabola, however with huge fluctuations around, the reasons can be bad convergency? too few k-points? too low MeshCutoff? The usual suspects... In principle, you should check the stability of your results vs. k- and mesh cutoffs. Good luck, Andrei +-- Dr. habil. Andrei Postnikov ----- Tel. +49-541-969.2377 -- Fax .2351 ---+ | Institut fuer Festkoerperforschung - FZ Juelich, D-52425 Juelich, Germany | +-- [EMAIL PROTECTED] --------- http://www.home.uni-osnabrueck.de/apostnik/ --+
