How to completely avoid "aliasing errors"?
Posted: Tue May 09, 2017 4:08 pm
Dear all,
I have some questions about the "aliasing errors". I have set PREC=accurate in INCAR, but there are still warnings in the OUTCAR. Why?
For example, in one job, I set PREC=accurate. The info written in OUTCAR is
dimension x,y,z NGX = 84 NGY = 80 NGZ = 210
dimension x,y,z NGXF= 168 NGYF= 160 NGZF= 420
I would recommend the setting:
dimension x,y,z NGX = 83 NGY = 79 NGZ = 208
The FFT grid with 83, 79, 208 is approximaly 2G_cut. So the actual values used in calculation 84, 80 and 210 have already exceeded the 2G_cut. But in the following there are two warnings
WARNING: aliasing errors must be expected set NGX to 86 to avoid them
WARNING: aliasing errors must be expected set NGY to 82 to avoid them
Can I ask why this warning happen?
Is there any parameters in INCAR which can guarantee to avoid "aliasing errors"? It seems that PREC=accurate is not enough.
Thanks!
Best,
Binglun
I have some questions about the "aliasing errors". I have set PREC=accurate in INCAR, but there are still warnings in the OUTCAR. Why?
For example, in one job, I set PREC=accurate. The info written in OUTCAR is
dimension x,y,z NGX = 84 NGY = 80 NGZ = 210
dimension x,y,z NGXF= 168 NGYF= 160 NGZF= 420
I would recommend the setting:
dimension x,y,z NGX = 83 NGY = 79 NGZ = 208
The FFT grid with 83, 79, 208 is approximaly 2G_cut. So the actual values used in calculation 84, 80 and 210 have already exceeded the 2G_cut. But in the following there are two warnings
WARNING: aliasing errors must be expected set NGX to 86 to avoid them
WARNING: aliasing errors must be expected set NGY to 82 to avoid them
Can I ask why this warning happen?
Is there any parameters in INCAR which can guarantee to avoid "aliasing errors"? It seems that PREC=accurate is not enough.
Thanks!
Best,
Binglun