Hi all,

I am currently using Qchem 6.0 and according to the manual it is possible to compute two-photon absorption cross-sections (TPAs) with ADC methods through the matrix inversion technique using the keyword ADC_PROP_TPA, however in the output I don’t find this information. If I include the keyword ADC_PROP_ES2ES I am able to recover TPAs but computed with the Sum over states expressions which is not the quantity I am interested in.

This is the input that I am using:

##
$molecule

0 1

O 0.000000 0.000000 -0.069903

H 0.000000 0.757532 0.518435

H 0.000000 -0.757532 0.518435

$end

$rem

METHOD adc(2)

BASIS aug-cc-pvdz

AUX_BASIS rimp2-aug-cc-pvdz

ADC_PROP_ES True

ADC_PROP_TPA True

EE_STATES [1,1,0,1]

$end

and this is the part of the output related to one of excited states:

Excited state 1 (singlet, B2) [converged]

Term symbol: 1 (1) B2 R^2 = 7.51604e-07

Total energy: -76.0072675789 a.u.

Excitation energy: 6.967051 eV

Osc. strength: 0.054586

Trans. dip. moment [a.u.]: [ -0.000000, -0.565506, -0.000000]

<i|r^2|0> [a.u.]: [ 0.000000, -0.000000, -0.000000]

Dip. moment [a.u.]: [ 0.000000, 0.000000, 0.690673]

Total dipole [Debye]: 1.755515

<r^2> [a.u.]: [ 15.147806, 10.478238, 13.978771]

Total <r^2> [a.u.]: 39.604816

V1^2 = 0.9292, V2^2 = 0.0708

##
Important amplitudes:

occ i occ j vir a vir b v

---------------------------------------------------------

1 (B2) A 4 (A1) A 0.6139

1 (B2) A 6 (A1) A 0.2067

---------------------------------------------------------

As you can see there is no trace of TPAs, do you know if I am doing anything wrong?

Best Regards,

Carmelo