I have done a RT-TDDFT calculation that was stopped before finishing. I restarted it and it resumed from the last saved checkpoint as expected (a few time steps before the last time step previously calculated). When i compared fragment charge and dipole moment of the recalculated time steps with those previously calculated, they were both different:
Total charge of the first fragment vs time
Initial calculation
...
839.80000 -7.079210205400E+001
840.00000 -7.079139863826E+001
840.20000 -7.079034211879E+001
840.40000 -7.078864903884E+001
840.60000 -7.078666342819E+001
840.80000 -7.078418324505E+001
841.00000 -7.078199092129E+001
Restarted calculation
839.80000 -7.079210205400E+001
840.00000 -7.079016993950E+001
840.20000 -7.078538055498E+001
840.40000 -7.077990397372E+001
840.60000 -7.077981413108E+001
840.80000 -7.077998404146E+001
841.00000 -7.078424785058E+001
...
Restarted calculation resumes at t=839.8a.u. and prints exactly the same charge as before, but at t=840a.u. and subsequent time steps the results differ.
1) Shouldn't i get identical results for a resumed calculation?
2) How exactly is the charge of each fragment calculated at each time step after propagation of the density matrix?
Thanks,
Andreas
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