ATKError

[alan]

i want to calculate the dos ,while i have optimized the structure. i have saved an opt.nc file in the optimize.and i used the initial density by restoring the opt.nc,also i save anther checkpoint file dos.nc.and it does not work for the error:
Traceback (most recent call last):
  File "111spin-trans.py", line 345, in ?
    runtime_parameters = runtime_parameters
ATKError: inverse(DZMatrix const &) : Could not LU factorize!
what can i do ?
and i have some  other questions :
should i have to save the nc file of each calculation? or is it necessary for optimize?
is the nc file of opt equal to the nc file of scf?because we want to use the scf.nc file for farther calculation like the calculation of dos.i think may be it can save time of calculation.

[Anders Blom]

It's hard to know exactly what goes wrong in your case, but generally speaking this error arises for 3 reasons:

* The use of the constraint "DensityMatrix" when the system converges to zero charge
* Atoms placed on top of each other
* Converging to very low tolerance, like 1e-16

In general the final NC file produced by a the optimization is indeed a properly converged calculation, so you don't actually need to rerun the calculation, just restore it and perform the analysis tasks. Also take care to extract the optimized geometry from the VNL file!

Perhaps, when I think about it, your problem is a simple matter of removing the checkmark for "Only use initial density" on the self-consistent tab in the NanoLanguage Scripter in VNL?