UT theoretical chemistry code forum

Dear Sir,

Can I use smaller ENCUT value in INCAR and only gamma poiot in KPOINTS file to lower the calculation cost of CI-NEB?

Because I only care about the reaction barrier not the reaction pathway, during TS-searching, I want to use low-fidelity parameters, such as low ENCUT=200eV and gamma point only, to roughly determine the reaction pathway, and then optimize the transition-state with high precise parameters to get the reaction barrier.

Is the scheme feasible? What I worry about is whether CI-NEB calculation with such low-fidelity parameters can find the right reaction pathway.

Absolutely! It is generally more efficient to find your reaction pathway and saddle using the least expensive parameters possible (low encut, soft potentials, minimal kpoint sampling, auto lreal, prec=normal, ... ). It is generally very little work to reconverge a saddle point with more accurate parameters. It is also important to know how well converged your calculation is with respect to the simulation parameters, so you need to do this kind of comparison anyway.

Thanks very much!