# Question about charge difference density and transition density!

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 Ylniu Member Profile Send PM
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 11:13:08 PM PDT - Thu, May 8th 2014 Dear all, I want to calculate the charge difference between excited state S1 and ground state S0, \rho_{S1}(r) - \rho_{S0}(r) and transition density between S1 and S0: \rho_{S1, S0}(r) = \phi^*_{S1}(r) * \phi_{S0}(r) But I did not find the keyword to do this in NWchem. Could anybody tell me how to calculate these densities? Thanks very much in advance.

 Huub Forum:Admin, Forum:Mod, NWChemDeveloper, bureaucrat, sysop Profile Send PM
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 10:51:33 AM PDT - Fri, May 9th 2014 Hi Ylniu, I am not sure whether NWChem supports calculating those quantities. But before I can say for sure I would need to know which code module you are using. Could you let me know, please? Huub

 Ylniu Member Profile Send PM
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 4:57:05 PM PDT - Sun, May 11th 2014 Dear Huub, I use nwdft/lr_tddft to calculate the excited states with TDDFT. I can get the eigenvectors of excited states, which represented the coefficients of the transition density matrix. But to generate the transition density cube is not easy to me. For Difference density, I do not understand its definition, because I do not understand how to define the total density of excited state. From the eigen-equation of TDDFT. We can get the coefficients of the transition density matrix. But how to generate the total density of the excited state from the transition density? For the reference: Filipp Furche, On the density matrix based approach to time-dependent density functional response theory, J. Chem. Phys., 2001, Vol. 114, Pages: 5982-5992. Eq(49).  Thanks for your reply and kind help!  Edited On 9:43:51 AM PDT - Wed, Jul 23rd 2014 by Edoapra

 Heully Member Profile Send PM
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 7:47:01 AM PDT - Wed, Jul 23rd 2014 XDM energy I am using the lest development version, 07. When I look at the total energy after convergence I think that this does not include the contribution of the dispersion XDM. Is that normal and this contribution should be added by hand ? jean-louis

 Edoapra Forum:Admin, Forum:Mod, bureaucrat, sysop Profile Send PM
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 9:43:05 AM PDT - Wed, Jul 23rd 2014 Jean-Louis, please see post http://www.nwchem-sw.org/index.php/Special:AWCforum/st/id1361/xdm_and_total_energy.html Edited On 9:44:39 AM PDT - Wed, Jul 23rd 2014 by Edoapra

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