report Bug in VASP5.2.12
Posted: Fri Aug 26, 2011 11:45 am
I have tried to solve the strange problem in VASP5.2.12 for a long time and now I found what the problem is in VASP5.2.12.
First, I start the calculations using VASP5.2.2 and VASP5.2.12 with the same input to check the problem. Using VASP5.2.2, the structure can easily converge to reach our criteria (EDIFFG = -0.01) but using VASP5.2.12 the structure cannot relax to reach the criteria and the calculation always stop with the following massage;
ZBRENT: fatal error in bracketing
please rerun with smaller EDIFF, or copy CONTCAR
to POSCAR and continue
After comparing the results obtained from VASP5.2.2 and VASP5.2.12, I found that the results of n-local (FORCE) are too different. Therefore, I believed that this must be the cause of problem. After checking codes, I found that n-local was calculated by calling subroutine in nonlr.F and nonl.F. Therefore, I try to replace nonlr.F and nonl.F in VASP5.2.12 with those in VASP5.2.2.
After modifying the codes, the structure can easily converge and reach the criteria as VASP5.2.2 did.
I thought that this may be a problem in VASP5.2.12 and hope you can fix this problem.
Now, I'm not sure that our calculation result is still valid.
I have to note that you will found this problem when you perform the calculation in defect cell. For bulk or perfect cell, there is no problem because of the symmetry.
<span class='smallblacktext'>[ Edited ]</span>
First, I start the calculations using VASP5.2.2 and VASP5.2.12 with the same input to check the problem. Using VASP5.2.2, the structure can easily converge to reach our criteria (EDIFFG = -0.01) but using VASP5.2.12 the structure cannot relax to reach the criteria and the calculation always stop with the following massage;
ZBRENT: fatal error in bracketing
please rerun with smaller EDIFF, or copy CONTCAR
to POSCAR and continue
After comparing the results obtained from VASP5.2.2 and VASP5.2.12, I found that the results of n-local (FORCE) are too different. Therefore, I believed that this must be the cause of problem. After checking codes, I found that n-local was calculated by calling subroutine in nonlr.F and nonl.F. Therefore, I try to replace nonlr.F and nonl.F in VASP5.2.12 with those in VASP5.2.2.
After modifying the codes, the structure can easily converge and reach the criteria as VASP5.2.2 did.
I thought that this may be a problem in VASP5.2.12 and hope you can fix this problem.
Now, I'm not sure that our calculation result is still valid.
I have to note that you will found this problem when you perform the calculation in defect cell. For bulk or perfect cell, there is no problem because of the symmetry.
<span class='smallblacktext'>[ Edited ]</span>