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PBE0 cannot be used in vasp5.2?
Posted: Mon Aug 24, 2009 6:45 am
by yuanxun
DEAR ALL:
why the label "LHFCALC" can not be used in vasp5.2?
The calculation seems to get into endless loop after five interaction without any output any more.
Thanks!
PBE0 cannot be used in vasp5.2?
Posted: Sun Aug 30, 2009 9:57 am
by alex
The first 5 iterations are DFT only, then exact exchange is calculated. This is _very_ time consuming. Try a small system.
Cheers
Alex
PBE0 cannot be used in vasp5.2?
Posted: Sat Jan 09, 2010 6:28 pm
by VASP001
[quote="yuanxun"]DEAR ALL:
why the label "LHFCALC" can not be used in vasp5.2?
The calculation seems to get into endless loop after five interaction without any output any more.
Thanks! [/quote]
You can check the file of OUTCAR ,to find the LHFCALC=.TRUE. or .FALSE.
PBE0 cannot be used in vasp5.2?
Posted: Thu Mar 04, 2010 1:45 pm
by Danny
the first 5 iterations are the normal speed (as alex mentioned) after this it becomes very slow, we are talking about orders of magnitude:
A small example of a single atom fcc system with 5x5x5 k-points and HSE06 calculation...there are only 10 kpoints in the IBZand the the steps become 100x slower than the first 5:
LOOP: cpu time 8.38: real time 8.38
LOOP: cpu time 2.46: real time 2.46
LOOP: cpu time 2.13: real time 2.14
LOOP: cpu time 2.08: real time 2.08
LOOP: cpu time 3.09: real time 3.09
LOOP: cpu time 311.79: real time 312.30
LOOP: cpu time 288.99: real time 289.54
LOOP: cpu time 285.76: real time 286.52
LOOP: cpu time 284.03: real time 284.25
LOOP: cpu time 282.32: real time 282.33
LOOP: cpu time 285.06: real time 285.34
LOOP: cpu time 281.36: real time 281.36
LOOP: cpu time 279.80: real time 279.81
LOOP: cpu time 283.62: real time 283.74
LOOP: cpu time 288.30: real time 289.55
LOOP: cpu time 287.12: real time 287.44
LOOP: cpu time 285.60: real time 286.15
LOOP: cpu time 286.33: real time 286.51
LOOP: cpu time 286.84: real time 287.50
Cheers Danny
PBE0 cannot be used in vasp5.2?
Posted: Thu Mar 04, 2010 4:30 pm
by admin
it is the exact exchange part which makes the calculation slow down.
whenever possible, use a k-mesh that cen be reduced for the exact-exchange contributions so you can make use of NKRED
PBE0 cannot be used in vasp5.2?
Posted: Fri Mar 05, 2010 8:57 am
by Danny
What are the properties of a k-mesh that can be reduced?
eg: k-point mesh Nx*Ny*Nz
with Nx a integer multiple of NKREDX, Ny of NKREDY and Nz of NKREDZ?
Danny
PBE0 cannot be used in vasp5.2?
Posted: Wed Oct 13, 2010 7:38 am
by Sonny
I dont really undrestand this manual entry for NKRED.
http://cms.mpi.univie.ac.at/vasp/vasp/W ... plied.html
I cant get this to work at all with various entries. =>
k-point set generating an fcc lattice -> 4 k-points in BZ
0
diret
0.5 0.5 0.0
0.0 0.5 0.5
0.5 0.0 0.5
0 0 0
Is it intended that ISEMAR=-5 is used with this set??
Do i need to get the Wavecar first?
Is it suitable for a loopscript?
<span class='smallblacktext'>[ Edited Wed Oct 20 2010, 02:59PM ]</span>