TD-DFT calculations with TDA

[eliezer]

Hello everyone,

I am new in DALTON and I am trying to do some TD-DFT calculations with the Tamm-Dancoff approximation (TDA) to analyse the allowed transitions for triplet absorption of some small molecules (around 50 atoms). For a commom TD-DFT I was using the following Keywords in "**RESPONSE" part:

**RESPONSE
*LINEAR
.SINGLE RESIDUE
.TRIPLET
.DIPLEN
.PRINT LEVEL
5
.ROOTS
20

Now, in order to use TDA, reading the manual I saw I had to use the Keyword ".TDA" inside the "**RESPONSE". So, doing this, I have now:

**RESPONSE
.TDA
.TRPFLG
*LINEAR
.SINGLE RESIDUE
.TRIPLET
.DIPLEN
.PRINT LEVEL
5
.ROOTS
20

However, every time that I use ".TDA", the calculation fail due to a syntax error. Anybody could help me to solve this?

Thank you in advance!
Best regards,
Eliezer

[kennethruud]

It would be helpful if you could upload your output file so we can see what kind of a syntax error message you actually get.


Best regards,

Kenneth

[taylor]

Can I add my usual comment here? (Look for my postings: I am not prepared to keep re-posting!) But of your 20 requested roots, if you are very lucky the lowest four or five may have some meaning. The rest will be garbage. It is just fantasyland to think that we can get a meaningful description of twenty roots at this level of calculation.

Best regards
Pete

[janus]

Try to move the .TDA keyword down into the *LINEAR section (where it's meant to go).

[taylor]

Very good suggestion to make the calculation run, but three-quarters of the results will still be garbage...!

Best regards
Pete

[janus]

Not my problem