SMALLDIST keyword

ioikonom

Hello,

I am trying to run a single-point calculation in a 2D heterostructure that I had optimized in the past using a different code.

I am taking the following error in the output file, which implies a problem with geometry.

**NEIGHBORS OF THE NON-EQUIVALENT ATOMS

N = NUMBER OF NEIGHBORS AT DISTANCE R
ATOM N R/ANG R/AU NEIGHBORS (ATOM LABELS AND CELL INDICES)
DISTANCE BETWEEN ATOMS 1 290 TOO SMALL: 0.3226 ANGSTROM
PLEASE CHECK GEOMETRY
ERROR **** NEIGHB **** USE KEYWORD SMALLDIST TO RUN ANYWAY**

However, I haven't yet managed to find in the tutorials or in the manual the keyword SMALLDIST.
Any suggestions?

Thanks in advance,
Ilias

GiacomoAmbrogio

Hi Ilias,

Even though it’s not documented in the manual, you can use the SMALLDIST keyword (in gemetry section of the input) to convert that error into a warning and allow the calculation to proceed. However, please note that atoms placed very close together can lead to numerical instabilities and linear dependencies in the basis set. Therefore, it’s important to carefully check your geometry and computational setup (i.e., basis set, TOLINTEG, etc.) before continuing.

ioikonom

Hi Giacomo,

Many thanks for your answer and suggestions.
It works and will do a double check for the geometry.

Have a good day,
Ilias