accurate forces for nonperiodic calculation

[Noam]

On Wednesday, October 15, 2014 1:19:59 PM UTC-4, Noam Bernstein wrote:
>
> Hi all - I'm trying to do a calculation for a molecule in vacuum, with 
> the nonperiodic MT solver, and I'd like to get the most accurate 
> forces I can, and by that I mean with minimal egg-box effects, and 
> consistent with the energy. 
>
> It's an organic molecule, which I'm doing with BLYP and DZVP basis 
> sets.  What do I need to converge with respect to, and do these values 
> seem reasonable? 
>
> CUTOFF 400 eV 
> CUTOFF_REL 60 eV 
>
> EPS_SCF 1.0e-8 (inner and outer) 
> XC_DERIV NN10_SMOOTH 
> XC_SMOOTH_RHO NN10 
>
> I can't use USE_FINER_GRID in &XC_GRID because it conflicts with the 
> MT solver I'm using. 
>
>
I just noticed that the original message said eV for the cutoff, which is 
wrong, since I'm using the default units which are Ry. 

In any case, does no one have any suggestions for how to get egg-box forces 
below 0.01 eV/A? I can relax the molecule and get the forces lower, but if 
I rotate it (to align with the cartesian axes) the forces jump back to 0.01 
eV/A, and I'd like them to stay about 10 times smaller.

      thanks,
      Noam
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