TDDFT plots
Clicked A Few Times
9:51:16 AM PDT - Fri, May 17th 2013
Does TDDFT calculations with NWChem.6.1 provides with oscillator strength and not actual intensity? Is there any way to get the actual intensities along with oscillator strength? A clue would be of much help. I have gone through the slides of NWChem presentation in which there was a test calculation for TDDFT of water molecule.

http://institute.loni.org/NWChem2012/documents/2_NWChem_Intro.pdf
(page 26-27)
I was able to reproduce the roots in terms of excitation energy but the intensity in the particular plot has a factor for the oscillator strength. The values are also too low to be the extinction coefficient. What exactly could be the y-axis and its relation with the oscillator strength? Any help would be appreciated. Thanks in advance.
Best regards,

Forum Regular
9:42:58 AM PDT - Mon, May 20th 2013
Hi, The dipole oscillator strengths are the intensities. It is calculated as the dipole transition squarred for the three components (x,y,z). Can you send me more details regarding what you are interested in calculating ? Can you send me the reference that you are trying to compare to ?

Best,
-Niri

niri.govind@pnl.gov

Clicked A Few Times
9:47:45 PM PDT - Tue, May 21st 2013
Thanks for your reply. Can you please let me know what are the values of the y-axis in the particular slide 27, since they are not the oscillator strengths. Thanks in advance.

Forum Regular
1:33:42 PM PDT - Wed, May 22nd 2013
Dear Himadri,

The graph is Gaussian/Lorentzian broadened spectra. You can process the TDDFT output using the nw_spectrum.py scripts in /contrib/parsers.

Best regards,
-Niri

Clicked A Few Times
11:39:07 AM PDT - Tue, Jun 25th 2013
I encounter the following error when I attempt to process the TDDFT output using the nw_spectrum.py script. Can you please suggest regarding identifying the error and where I should modify the script. Any help is highly appreciated. Thanks in advance.

$ python nw_spectrum.py -b0.3 -p5000 -wnm < tddft_water.nwo > spectrum.dat
Traceback (most recent call last):
 File "nw_spectrum.py", line 640, in <module>

   main()

 File "nw_spectrum.py", line 603, in main

   roots = parse_input_tddft (opts)

 File "nw_spectrum.py", line 285, in parse_input_tddft

   raise Exception ("Failed to convert root values: {0}".format(line_strip))
Exception: Failed to convert root values: Root 1 singlet b2 0.294221372 a.u. 8.0062 eV

Clicked A Few Times
4:03:14 PM PDT - Wed, Jun 26th 2013
Commenting out line 282 resolved the problem. Kindly ignore the previous post. Thank you very much.


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