IR frequency calculations

From NWChem

Viewed 504 times, With a total of 1 Posts
Jump to: navigation, search

Clicked A Few Times
Threads 4
Posts 6
Hello All,

I am having an equilibrated structure of a set of atoms from classical MD simulations.
I want to calculate the IR frequencies for this particular structure obtained from MD as it is without performing any geometry optimization.

Is there a way I can do that??

Thanks in advance,
Aniruddha M Dive

  • Niri Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop
    Profile
    Send PM
Forum Regular
Threads 4
Posts 191
Hi Aniruddha,

Is your classical MD simulation in the condensed phase ? If so, you should be able to calculate the vibrational spectra with the information you have from the MD simulation. Basically, you calculate the autocorrelation function of the velocities. This will give you the vibrational density of states. This will include both IR and Raman modes. To calculate the IR specifically, you need to calculate the autocorrelation function of the molecular dipole.

If you have a molecular system and if you want to calculate the IR at the DFT level of theory, then define the geometry in the geometry block and ask for task dft frequencies. See the following link for more information

http://www.nwchem-sw.org/index.php/Release66:Hessians_%26_Vibrational_Frequencies

Hope this helps.

Best,
-Niri

niri.govind@pnnl.gov


Forum >> NWChem's corner >> QMMM



Who's here now Members 0 Guests 0 Bots/Crawler 1


AWC's: 2.5.10 MediaWiki - Stand Alone Forum Extension
Forum theme style by: AWC