vaspÓÅ»¯½á¹¹±¨´íZBRENT: fatal error in bracketing
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ZBRENT: fatal error in bracketing
please rerun with smaller EDIFF, or copy CONTCAR
to POSCAR and continue
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2. IBRION¸ÄΪ1¼ÆË㣬ÏÖÔÚÒѾËãÁË120¸öÀë×Ó²½ÁË»¹Î´ÊÕÁ²£¬ÓÅ»¯½á¹¹ºóÃæʵʱ¸üС£
3. IBRION=1£¬²¢ÇÒADDGRID=TRUE½øÐÐÓÅ»¯£¬ÓÅ»¯½á¹¹ºóÃæ¸üС££¨ADDGRID¼òµ¥²âÊÔÁËһϣ¬Ëƺõ¶ÔÄÜÁ¿Ã»ÓÐʲôӰÏ죩
4. IBRION²»±ä£¬ÈÔÈ»=2£¬¼ÓÈëADDGRID=TRUE½øÐÐÓÅ»¯£¬½á¹ûºóÃæ¸üС£
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4. ADDGRIDµÄ¾ßÌ庬ÒåÊÇʲô£¬ÓÐʲôӰÏ죿vasp¼ÆËãºÃÏñºÜÉÙ¿´µ½Õâ¸ö²ÎÊý¡£
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INCAR:
SYSTEM = LiFePO4_1
######Start Parameter for This Run
ISTART = 0
ICHARG = 2
INIWAV = 1
######Electronic Relaxation
ENCUT = 520
NELM = 60
EDIFF = 1E-5
GGA = PE
ISMEAR = 0
SIGMA = 0.05
PREC = Accurate
ISPIN = 2
#LORBIT = 10
######Ion Relaxation
IBRION = 2
ISIF = 2
NSW = 200
EDIFFG = -0.01
POTIM = 0.5
ALGO = Fast
LREAL = A
NPAR=4
######LDA+U
LMAXMIX = 4
LDAU = .TRUE.
LDAUTYPE = 2
LDAUL = 2 -1 -1 -1
LDAUU = 5.3 0 0 0
LDAUJ = 1.0 0 0 0
#for out
LCHARG = .FALSE.
LWAVE = .FALSE.
LVTOT = .FALSE.
LELF = .FALSE.
KPOINTS:
k-points
0
Monkhorst Pack
4 3 4
0 0 0
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http://cms.mpi.univie.ac.at/vasp ... ?f=3&t=7415
ÑeÃæµÄ admin (Ò²¾ÍÊÇ VASP ¹Ù·½Õ“‰¯µÄ¹ÜÀí†T£¬Éí·Ýëm²»´_¶¨£¬µ«~ Ò»¶¨¸ú VASP ×÷ÕßȺÓÐÖ±½ÓêPßB)
please have a look at the OUTCAR file, at the forces of the last ionic step before Brent's algorithm fails
-- if the calculation is very well-converged already, please proceed using IBRION=1; ADDGRID=.TRUE. and a larger ENCUT
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-- if this error appears at an early stage of the relaxation, pelase check if your input geometry was reasonable, eg by having a look at the interatomic distances (written in OUTCAR) or the forces of the first geometries. It may then help to increase the accuracy (PREC= Accurate and a higher ENCUT) and to decrease POTIM to avoid too large stepwidhts in the first relaxation step.
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™z²é OUTCAR ƒÈµÚÒ»‚€ ionic loop µÄ FORCE£¬¿´¿´ÊÇ·ñÓÐÔ×Ó³ö¬F²»Œ¤³£´óµÄÊÜÁ¦
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http://cms.mpi.univie.ac.at/vasp ... p?f=3&t=869
this message says that during geometry optimisation no reasonable next step could be found with Brent's algorithm (linear bisectioning)
please check the following
1) is the system converged already? (look at the forces in OUTCAR, especially if you use the total energy change as congvergence criterium for ionic optimisation)
2) if not: is each ionic step converged electronically ( this is needed to obtain reasonable forces)
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sometimes, if the calculation is already highly converged, vasp cannot interpolate the next step to within the numerical accuracy because it simply would be so small. (this behaviour is machine-dependent). If you have used IBRION=2, it may help to switch to IBRION=1 and set ADDGRID=.true. in addition
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http://cms.mpi.univie.ac.at/vasp-forum/viewtopic.php?t=1856
ZBRENT is an algorithm search for a root of a function by Brent's method: Numerical recipies, Section 9.3
The problem in your case might be that the Conjugate Gradient algorithm (IBRION=2) is not suitable for very small corrections of the atomic positions if your system has almost reached equilibrium (please have a look at XDATCAR to check the size of the relaxation steps done before the ZBRENT warnings show up). Usually it is sufficient to converge a system up to maximum remaining forces of about 0.01eV/A (EDIFFG=-0.01).
please try one of the following:
1) choose a different algorithm for ionic optimization (IBRION=1)
2) set ADDGRID=.True. in INCAR (only for vasp releases 4.4.5 and newer)
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