steps of bulk calculation to determine the optimized parameters
Posted: Sun Mar 08, 2009 8:35 am
Hi, users,
I am a rookie to vasp, I want to do some NEB calculations to get metal on metal suface diffusion barrier. Following the manual, some bulk calculations are needed in advance to get optimized parameters for later surface calculation. However, I don't think the process described in the manual are clear enough to me. I design a process based on the manual's description. I want to know whether this process is sufficient to get the right parameters.
step1: PREC=H,ISMEAR=-5,ENCUT=default in POTCAR / loop in a set of kpoints, kpoint is determined if deltaE<0.001eV
step2: PREC=H, ISMEAR=1,ENCUT=default in POTCAR, KPOINTS=kpoint_step1 / loop in a set of SIGMAs, SIGMA is determined if T*S<0.001eV
step3: PREC=H, ISMEAR=1,SIGMA=sigma_step2,ENCUT=default in POTCAR / loop in a set of kpoints, the target accuracy is the same with step1
step4: PREC=H, ISMEAR=1,ENCUT=default in POTCAR, KPOINTS=kpoint_step3 / loop in a set of SIGMAs, SIGMA is determined if T*S<0.001eV
step 5: PREC=H, ISMEAR=1,SIGMA=sigma_step4,KPOINT=kpoint_step3 /loop in a set of ENCUTs, deltaE<0.001eV is cosidered converged
step 6: PREC-H, ISMEAR=1, SIGMA=sigma_step4, KPOINT=kpoint_step3,ENCUT=encut_step5 / loop in a set of volumn, get the corresponding energy.
step 7: fit the data get in step6 Birch–Murnaghan equation of state , then equilibrium volumn is obtained.
I hope I am clear, this process get reasonable result, but I still want to get some ideas on this process.
Thank you.
I am a rookie to vasp, I want to do some NEB calculations to get metal on metal suface diffusion barrier. Following the manual, some bulk calculations are needed in advance to get optimized parameters for later surface calculation. However, I don't think the process described in the manual are clear enough to me. I design a process based on the manual's description. I want to know whether this process is sufficient to get the right parameters.
step1: PREC=H,ISMEAR=-5,ENCUT=default in POTCAR / loop in a set of kpoints, kpoint is determined if deltaE<0.001eV
step2: PREC=H, ISMEAR=1,ENCUT=default in POTCAR, KPOINTS=kpoint_step1 / loop in a set of SIGMAs, SIGMA is determined if T*S<0.001eV
step3: PREC=H, ISMEAR=1,SIGMA=sigma_step2,ENCUT=default in POTCAR / loop in a set of kpoints, the target accuracy is the same with step1
step4: PREC=H, ISMEAR=1,ENCUT=default in POTCAR, KPOINTS=kpoint_step3 / loop in a set of SIGMAs, SIGMA is determined if T*S<0.001eV
step 5: PREC=H, ISMEAR=1,SIGMA=sigma_step4,KPOINT=kpoint_step3 /loop in a set of ENCUTs, deltaE<0.001eV is cosidered converged
step 6: PREC-H, ISMEAR=1, SIGMA=sigma_step4, KPOINT=kpoint_step3,ENCUT=encut_step5 / loop in a set of volumn, get the corresponding energy.
step 7: fit the data get in step6 Birch–Murnaghan equation of state , then equilibrium volumn is obtained.
I hope I am clear, this process get reasonable result, but I still want to get some ideas on this process.
Thank you.