Print molden file each MD step


Do you know a way to print molden files for each step during MD?

I am intereseted in the analysis of QTAIM properties in each step of a excited state MD

Best regards!

It looks like MOLDEN_FORMAT=2, along with PRINT_ORBITALS=TRUE, will do the trick. (I implemented this long ago to print Molden at each step of a geometry opt and it seems to work for AIMD also.) I tried the following test job, which is sample job with one line added:

The following job run AIMD using B3LYP energies and gradients.
MO coefficients are printed at each time step when
aimd_print>=2 and print_orbitals>0

0 1
H 1 0.95
H 1 0.96 2 104.5

jobtype           aimd
exchange          b3lyp
basis             6-31G*
time_step         15
aimd_steps        10 
aimd_init_veloc   zpe
aimd_init_veloc   thermal Boltzmann distribution  
aimd_temp         300     (in Kelvin)
aimd_print        2
print_orbitals    10 print ALL occupied and 10 virtuals
debug_random_seed true
molden_format  2 ! added this to get Molden file at each step

I assume (?) that QTAIM can use the occupied MOs to get the density and perform the analysis? Because those are all you will get from the Molden file.

Thank you for the response!

Although wfn/wfx files are used to QTAIM analysis, I have had problems with wfn files printed by q-chem. For this reason I am trying the molden format to construct the electron density and then analyze it.

But, do you have a similar implementation for printing wfn each MD/opt step?
I think it’s not bad to know it.


I have not used QTAIM and therefore haven’t used the .wfn file. I ran a test job with

WRITE_WFN     filename

in the $rem section, and I do get back filename.wfn, with data structures that look reasonable. If you’re not able to process that file with QTAIM then please send a bug report to Q-Chem.

At present, the structure of the code does not allow the .wfn file to be printed at every step (either for geometry optimization or AIMD), because it’s set up to write to a single user-specified file name. That’s fixable (in a future version of the code), but you would need to submit a feature request to Q-Chem.