single point dft energy calculation gives different energies with and without noscf tag


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Hello

Just for a test run on H atomic energy. I was doing a "task dft energy" calculation with and without noscf tag in dft block. I obtained energies differing by 4e^-4 H=0.01 eV (not bad). I know doing such a calculation doesn't make sense but still I wanted to confirm that non self consistent cycles would give the same energies which is not the case.

Input file:

echo
title "cluster"


geometry autosym
H 20.995999999999999 13.741000000000000 13.047000000000001

end

basis "ao basis" cartesian
H library 6-311G**
end

dft
iterations 3000
direct
mult 2
XC xpbe96 cpbe96
convergence ncyds 3000
noscf
end

DRIVER
XYZ a.xyz
MAXITER 500
END

task dft energy