I am running single point calculations using DFT from dscf and CCSD from ccsdf12 of hydrogen chains with the series of basis sets {cc-pVDZ, cc-pVTZ, cc-pVQZ, cc-pV5Z} for basis set extrapolations.

When the chain is compressed to short internuclear separations (~1.0 Bohr) the calculations with larger basis sets explode after a few iterations.

I was expecting this behaviour as the basis sets become linearly dependent. Normally such linear dependence would be projected out of the basis set for overlap matrix eigenvalues < some threshold.

Is it possible to set this threshold in the control file?

I have found the option lindep in $ricc2 for the coupled cluster calculations, though I am not certain this is doing what I want, and it definitely doesn't apply for the DFT calculations.

Many thanks,

James