[CP2K-user] Problems computing LUMO energy for a non-periodic metallic cluster using PM6

Richard Marchese Robinson r.l.march... at leeds.ac.uk
Mon Jul 29 16:25:41 UTC 2019


Dear all,


Firstly, thanks to the developers for making this tool available to the 


I have only recently started using CP2K and I am hoping to be able to 
compute HOMO – LUMO gaps and individual energies for non-periodic, metallic 
clusters using different levels of theory. (It is my understanding from the 
literature that this gap should tend to zero as the clusters become larger.)


I am trying to perfom this calculation at the PM6 level of theory. 


I provide my input and output files. 


It is my understanding that the 22 eigenvalues in the output files refer to 
the energy levels of the occupied valence orbitals, with the Fermi energy 
corresponding to the energy of the HOMO.


However, as far as I can tell, I cannot obtain the LUMO energy. Am I 
overlooking something?


I have tried to address this using both the MO and MO_CUBES settings in the 
input files. I get a warning about the printing of MO cube files not being 
implemented for semi-empirical methods, e.g. PM6. Since this section is the 
only section which explicitly refers to the LUMO in the input file, does 
this mean PM6 LUMO values cannot be computed using CP2K?


I am running cp2k.7.0.190717.for.winxp.fftw3 on Windows 7.


Thanks in advance for any assistance you have time to provide.


Best regards,





Dr Richard Marchese Robinson

Post-Doctoral Research Associate

BioRima Project [https://www.biorima.eu/]

University of Leeds

United Kingdom
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