DFT problem: Range-separated functionals failing to converge for C70 fullerene


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Following up here in case this is ever useful to anyone else . . .

The effect of putting "Task DFT" in the wrong place seems to depend on installation or perhaps on version. The difference between the correct:


dft
xc xcamb88 1.00 lyp 0.81 vwn_5 0.19 hfexch 1.00
cam 0.33 cam_alpha 0.19 cam_beta 0.46
direct
print "information"
iterations 200
vectors output C70.movecs
end
task dft
scf
 semidirect memsize 100000000 filesize 0
end


and the incorrect


dft
xc xcamb88 1.00 lyp 0.81 vwn_5 0.19 hfexch 1.00
cam 0.33 cam_alpha 0.19 cam_beta 0.46
direct
print "information"
iterations 200
vectors output C70.movecs
end
scf
 semidirect memsize 100000000 filesize 0
end
task dft

leads version 6.0 on the NERSC computer Carver to simply crash with

"int2e_file: Failed to allocate cache ... halving"

However, on my home cluster, using version 6.1.1, putting "task dft" after the SCF calculation causes the calculation to run but produce wild energies. The effect on the energies of "task dft" being in the wrong place varies from calculation to calculation--some calculations run and converge even with "task dft" in the wrong place.

Hope this is helpful to someone. Thank you again Niri for your help.