Hello Everyone
I want to Calculate the Energy Barrier of Li-ion in a bulk material using VASP. I build my Images using nebmake.pl and I have 6 Images and total 8 folders(00-07).my Energy results are acceptable for the intermediate phases(01-06) and they seem OK. But as you know, when NEB Calculation is performed the first and the last folders have only POSCAR file and my question is how I can calculate the energy for these POSCAR files. are they necessary for reporting the value of activation energy?
Your first and last images correspond to the initial (reactant) and final (product) states of the system, so yes, their energy is required to calculate the activation energy.
Prior to performing NEB, you should have already optimized the initial and final system states and determined the energies of these two systems. The results you obtain for the intermediate states will be dependent on the initial and final state you provide, so you want to make sure these have been optimized.
In any event, you will want do a relaxation of the initial and final states using the same DFT setup (e.g., k-points, energy cutoff, pseudopotentials, XC functional, etc.) that was used for the intermediate states. For geometry relaxations, I normally set the following tags: IBRION = 2, POTIM = 0.35, EDIFFG = -0.05. These options optimize using the conjugate gradient algorithm, sets POTIM (a parameter that scales changes in atomic positions based on forces), and defines the force convergence criterion as 0.05 eV/angstrom.
Hope this helps!
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