Bond constrains in geometry optimization

[icamps]

Hi,

For the molecular dynamic calculations, it is possible to set up the parameter shake, that can constrain the atomic bonds.

I did a geometry optimization with xTB of a linear metal nanocluster (four Cd atoms in a row), and the result is that the cluster was break in half with two fragments of two Cd atoms each. I previously did (for other research) geometry optimization using DFT (with SIESTA and GAUSSIAN) and the cluster remain with all the atoms connected.

My question: is there a similar parameter for geometry optimization in order to force atoms to remain bonded?

Regards,

Camps