Assorted questions about RT-TDDFT.

Just Got Here
I am seeking advice in relation to real-time time-dependent DFT calculations:

1) Where can I find a description of how the molecular orbital occupations, printed via the
PRINT moocc
option (mentioned in, are computed (other than looking at the source code)? I guess they are the modulus squared of the overlaps between an occupied Kohn-Sham eigenstate at time t=0 and the same eigenstate at time t.

2) Is it possible to perform the real-time TDDFT simulation while keeping the atomic cores clamped to their t=0 positions?

3) I am interested in computing the time-dependent scalar products (or at least their squares) between (a) the time-dependent state at time t and (b) linear-response TDDFT states computed at t=0. Is there a way to perform such a calculation?

4) Is there any particular reference where I can read more about how RT-TDDFT is implemented in NWChem?

Thank you very much for your help.

Forum Regular
The answers to most of your questions can be found in the reference given in the documentation ( Specifically, K. Lopata, N. Govind, "Modeling Fast Electron Dynamics with Real-Time Time-Dependent Density Functional Theory: Application to Small Molecules and Chromophores", J. Chem. Theory Comput., 7, 1344 (2011)

1) The orbital occupations are calculated by projecting the time-dependent density onto the ground state orbitals, see equation 21 in the above referenced paper

2) This functionality is not implemented. You could try using pseudopotentials if you want to eliminate the core electrons from explicit consideration

3) There is nothing implemented that would achieve what you want

4) See above referenced paper

Just Got Here
Thank you for your answers, they were very helpful.

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