### Proper printing of two-photon tensors

Posted:

**09 Jul 2015, 10:06**Hi,

I know these are exotic properties but Dalton actually has an own keyword for the calculation of two-photon circular dichroism (.TPCD in the *QUADRA group). Using this keyword I get exactly what I want to calculate TPCD cross sections: Electric dipole-magnetic dipole transition tensors, electric dipole-electric dipole transition tensors and electric dipole-electric quadrupole transition tensors - all expressed in velocity gauge to get origin independent results. This is nice. But what is not so nice however, is that the printing of these results is extremely messy. Per state I need 36 different tensor elements, sometimes I even get 90 when also the DIPLEN operator is involved. It is not impossible to gather these elements from the output using a shell script but it is of course kind of painful as you cannot grep specific elements from the output as the operator labels are never printed in the same line as the tensor elements.

The amount of pain is even increased if the molecules get symmetry. Then the tensors are completely messed up and up to now I did not invest the effort to write a shell script for that. I think this could be way easier with some help from the Dalton developers. There is actually a very compact printing of the two-photon absorption tensor after a TPA calculation. Would it be possible to modify this such that also the other tensors can be printed in this way? To be precise this should be

1.) The electric dipole-electric dipole transition strength tensor in velocity gauge (DIPVEL/DIPVEL different elements per state)

2.) The electric dipole-magnetic dipole transition strength tensor in velocity gauge (DIPVEL/ANGMOM, 9 different elements per state)

3.) The electric dipole-electric quadrupole transition strength tensor in velocity gauge (DIPVEL/ROTSTR, 18 elements per state)

Then the evaluation of the data (which is rather complex for TPCD) would be way easier. Another thing which I would really appreciate for this tensor printing (also for the existing one) would be if we could get some more decimal places in the compact output. Thank you in advance for the effort!

I know these are exotic properties but Dalton actually has an own keyword for the calculation of two-photon circular dichroism (.TPCD in the *QUADRA group). Using this keyword I get exactly what I want to calculate TPCD cross sections: Electric dipole-magnetic dipole transition tensors, electric dipole-electric dipole transition tensors and electric dipole-electric quadrupole transition tensors - all expressed in velocity gauge to get origin independent results. This is nice. But what is not so nice however, is that the printing of these results is extremely messy. Per state I need 36 different tensor elements, sometimes I even get 90 when also the DIPLEN operator is involved. It is not impossible to gather these elements from the output using a shell script but it is of course kind of painful as you cannot grep specific elements from the output as the operator labels are never printed in the same line as the tensor elements.

The amount of pain is even increased if the molecules get symmetry. Then the tensors are completely messed up and up to now I did not invest the effort to write a shell script for that. I think this could be way easier with some help from the Dalton developers. There is actually a very compact printing of the two-photon absorption tensor after a TPA calculation. Would it be possible to modify this such that also the other tensors can be printed in this way? To be precise this should be

1.) The electric dipole-electric dipole transition strength tensor in velocity gauge (DIPVEL/DIPVEL different elements per state)

2.) The electric dipole-magnetic dipole transition strength tensor in velocity gauge (DIPVEL/ANGMOM, 9 different elements per state)

3.) The electric dipole-electric quadrupole transition strength tensor in velocity gauge (DIPVEL/ROTSTR, 18 elements per state)

Then the evaluation of the data (which is rather complex for TPCD) would be way easier. Another thing which I would really appreciate for this tensor printing (also for the existing one) would be if we could get some more decimal places in the compact output. Thank you in advance for the effort!