Priroda - Raman Intensities

[YuraM]

Good evening,

did someone try to calculate the Raman Intensities with Priroda? In my case it prints 0. May be I need to include some additional info in the input file?

[alxyppv]

I did, worked well. Please show (send) your input file.

[EvgeniX]

May be I need to include some additional info in the input file?

yeah, yeah

[YuraM]

$system mem=1800 disk=-10000
$end
$control
task=hessian
theory=DFT four=1
basis=basis4.in
print=+esr
$end
$optimize steps=350 tolerance=0.00045,0.0018 $end
$scf iterations=150 $end
$grid accuracy=1e-10 $end
$molecule
mult=1
charge=0
cart
set=L1

[YuraM]

Thank you! Do I have to specify something else to get the Raman intensities?

[alxyppv]

Для расчета производных поляризуемости надо задать task=dipole. Наверное можно скомбинировать task=hessian+dipole. Также в модуле можно задать величину поля field=0.001. Я уже не помню, сколько там по умолчанию. Вопрос в том, что если величина поля слишком большая, то оно уже влияет на элктронную струкутуру, а если слишком маленькая - то шумы слишком большие, надо с хорошей точностью все считать. Кроме того, если Вам нужны имеено интесивности, а не просто производные поляризуемости, а гессиан при этом не считается ибо был посчитан ранее (т.е. если делается task=dipole), то расчитанный ранее гессиан надо вставить в инпут

$control
task=dipole
field=0.001
$end

[YuraM]

Thank you! Yes, it works. I had to calculate the polarizabities first, and then run hessian calculation with inserted second second derivatives and polarizabilities. Just curious, is PBE/L1 OK? Would you suspect any improvement when going to PBE0 or L2?

[Гесс]

Thank you! Yes, it works. I had to calculate the polarizabities first, and then run hessian calculation with inserted second second derivatives and polarizabilities. Just curious, is PBE/L1 OK? Would you suspect any improvement when going to PBE0 or L2?

I wouldn't wonder if smth changes with going from PBE to PBE0. As far as i remember, smth nasty goes with RI-DFT that is obligator to hybrids.

[alxyppv]

I did computations with relatively simple systems (fullerenes), there was almost no difference - I mean, either I compute polarizablity derivatives by PBE0/6-31G or PBE/3z, Raman spectra are similar (i.e. no dramatic variations). It was very surprise for me, usually it is claimed that polarizability is very method and basis set dependent - but I did not see it at all.