### TD-DFT calculations with TDA

Posted:

**09 Aug 2016, 20:18**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

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