Questions tagged [spectroscopy]
For questions about or related to spectroscopy.
88 questions
5 votes
1 answer
79 views
Can DFT+VPT2 be used to calculate vibrational frequencies and intensities of infrared hot bands?
I usually calculate fundamental IR spectra of molecules (fluorocarbons with 11 to 26 atoms) using the ORCA software package (using DFT). I recently experimented with the VPT2 option in ORCA 6.0 to ...
- 51
7 votes
1 answer
235 views
NMR calculations using RI-MP2 in ORCA
I have been trying to do some NMR calculations for Zinc-BINAP-complexes that can benefit from GIAO (gauge-including atomic orbital) for 31P shieldings. I have read that GIAO is the go-to method for ...
- 665
4 votes
1 answer
66 views
Psi4 plugin PSIXAS: output format
Learning to use PSIXAS (a Psi4 plugin for calculating NEXAFS spectra). To get a spectrum, I need excitation energies and cross sections. Excitation energies are easy to find in the output. I do not ...
- 61
7 votes
0 answers
90 views
Negative values when computing absorption cross section
This question is related to a few other posts (1, 2, 3). With a 2D model of CO2 ($r_1$ and $r_2$ being the coordinates of interest), I am running the following (computational) experiments: Compute ...
- 936
7 votes
2 answers
852 views
How to verify that my molecules are geometry optimised?
I am trying to build a workflow which includes computational chemistry modules. As a component to that, essentially the first step, I am required to tightly optimize the structure of my molecule. To ...
- 203
3 votes
1 answer
184 views
Smilarity between TDDFT results (excitation energies, oscillator strength) obtained with CAM-B3LYP and M06-2X functionals
I've noticed that TD-DFT with CAM-B3LYP and TD-DFT with M06-2X give quite similar results (mainly regarding excitation energies, a bit less for oscillator strengths). Here is an example of 10 ...
- 763
5 votes
1 answer
78 views
Core-level spectroscopies in correlated mixed-valence compounds
I have recently attempted to simulate core-level spectra (XAS, RIXS, EELS) in correlated mixed-valence compounds, but I am at a loss of what method might describe these systems best. My go-to method ...
- 370
2 votes
0 answers
36 views
Xray spectroscopy of elemental Cobalt
Can anyone please share the image of elemental cobalt Xray spectroscopy image? Particularly I would like to see how it shows within 50-200 eV range (or close to this range). I have found some ...
- 891