UT theoretical chemistry code forum

The error message mentions the density-grid size (100 x 100 x 64). So check the grid parameters are suitable for your system. You may try refining the grid to see if it resolves the issue.

Check your initial guess for the NEB path is reasonable. It's often helpful to perform a non-spin-polarized NEB calculation first to obtain a good initial path and then switch to a spin-polarized calculation.