193. Notes on UV/VIS - TD DFT in nwchem

I've been interested in looking at using NWChem to predict UV/VIS spectra. This post doesn't show how to do it but is rather just a look at what affects the positions of absorbances.

(although it more or less just involves
tddft
       cis
       nroots 24
end
task tddft energy)

I chose benzene and water as test cases. 

Here's water:

water

Reference spectrum in gas phase: http://www.lsbu.ac.uk/water/vibrat.html (166.5 nm) which tallies very well with 3-21g and 6-31g, but not at all with 6-31++g** or 3-21++g*.

Here's benzene:

Reference spectrum: http://www3.wooster.edu/chemistry/is/brubaker/uv/uv_spectrum.html
The reference spectrum, while a bit diffuse, shows the main absorbance at ca 178 nm. Presumably that's in benzene, not water.

More basis sets:

(cat Benzene_631g/Outputs/nwch.nwout |egrep "Root|sci"|gawk '{print $4,$6}'>bz631g.dat)