Good,
So, If I want to search for an appropriate basis set for my system (which is big), an accuracy of which order is considered good ? i.e., If I compare to a reference highly accurate basis set, an error of 5.0*10^-3 atomic units is considered good.
By the way, this is approximately the difference which I get for a very simple system - the flour atom (dscf calculation, pbe functional, gridsize 7) with the following basis sets:
def2-TZVP --> -99.66912313248
def2-QZVP --> -99.67510981418
Thanks