I'm doing a static calculation. IBRION is set to-1, but NSW forgot to set it to 0. I found that the energy of the second ion step is not the same as that of the first ion step. The structure has not changed, so why is the energy different? Which result is reliable?
ALGO = Fast EDIFF = 1E-5 EDIFFG = -2E-2 ENCUT = 520 IBRION = -1 ICHARG = 1 ISIF = 2 ISMEAR = 0 POTIM = 0.05 ISPIN = 2 ISTART = 1 LORBIT = 11 LREAL = Auto #ADDGRID = True LWAVE = False LCHARG = False #MAGMOM = 30*0.6 NELM = 400 NSW = 000 PREC = Accurate SIGMA = 0.05 #SYMPREC = 1E-4 #ISYM = 0 IVDW = 1 NCORE = 4 LMAXMIX = 4 # DFT+U LDAU = True LDAUTYPE = 2 LDAUL = 0 0 2 0 LDAUU = 0 0 5.3 0 LDAUJ = 0 0 0 0 LDAUPRINT = 1
The result is:
1 F= -.12046558E+04 E0= -.12046422E+04 d E =-.272572E-01 mag= 2.0115 2 F= -.12047406E+04 E0= -.12047334E+04 d E =-.145517E-01 mag= 1.7560 3 F= -.12047407E+04 E0= -.12047334E+04 d E =-.145535E-01 mag= 1.7565 4 F= -.12047407E+04 E0= -.12047334E+04 d E =-.146082E-01 mag= 1.7569 5 F= -.12047407E+04 E0= -.12047333E+04 d E =-.146615E-01 mag= 1.7573 6 F= -.12047407E+04 E0= -.12047334E+04 d E =-.145626E-01 mag= 1.7575 7 F= -.12047407E+04 E0= -.12047334E+04 d E =-.145611E-01 mag= 1.7575 8 F= -.12047407E+04 E0= -.12047334E+04 d E =-.145244E-01 mag= 1.7579
I guess the result may be related to ICHARG=1, which causes the subsequent calculation to read the previous CHGCAR. If so, the energy of static calculation should be set to NSW=0 or NSW>1, and the convergent energy should be used.