[Wien] What is the meaning of NECxx in case.scf ?

[Stefaan Cottenier]

>   What is the meaning of the row in the file of
>case.scf?
>
>  :NEC01: NUCLEAR AND ELECTRONIC CHARGE  720.00000 719.99823   1.00000
>
>   You know the result of 720.00000 minus 719.99823 is
>0.00177.However,the last item of the listed row of
>case.scf is 1.00000.Why?

Because it is 720/719.99823 = 1.000002458, which is 1.00000 if you round it 
to 5 digits. :NEC gives you the number by which the actual charge density 
should be multiplied in order to give you the correct total number of 
electrons after integration. If everything is fine, this scaling factor 
should be very close to 1, as in your case.

Stefaan