faq:cholesky_decomp_failed

If you see the following error message (line number correct as of CP2K 2.7, Dec 2015), with a routine calling stack that includes `prepare_preconditioner`

, for example:

******************************************************************************* * ___ * * / \ * * [ABORT] * * \___/ CPASSERT failed * * | * * O/| * * /| | * * / \ fm/cp_fm_cholesky.F:94 * ******************************************************************************* ===== Routine Calling Stack ===== 10 cp_fm_cholesky_decompose 9 make_full_inverse_cholesky 8 make_preconditioner 7 prepare_preconditioner 6 init_scf_loop 5 scf_env_do_scf 4 qs_energies 3 qs_forces 2 qs_mol_dyn_low 1 CP2K

This says that CP2K failed to compute a Cholesky decomposition during the construction of the preconditioner for OT. Most likely, the overlap matrix (S) has become singular (or at least numerically close to singular). Here are some causes / possible solutions:

- Try some of the other PRECONDITIONER options, which may prove to be more stable for your system.
- Decrease the value of EPS_DEFAULT or EPS_PGF_ORB, to reduce the amount of numerical noise in the construction of S.
- Check carefully that the Basis Set(s) chosen for your calculation are appropriate for the system. If the basis set is over-complete this could result in a singular overlap matrix - try switching to a smaller basis set.

faq/cholesky_decomp_failed.txt · Last modified: 2015/12/14 21:04 by oschuett