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Re: Dependency of SCF convergence on CPU type

Thomas Pijper

Dear Yura,

As far as I know, CPU specific versions are only CPU specific because they use certain CPU instructions for speeding up calculations. If you use, for example, a version of Firefly optimized for 'AMD Barcelona/Intel Core 2 Duo and newer' on an old Pentium II CPU you would most likely get an error because Firefly would not be able to access the newer CPU instructions. Or, as another possibility, Firefly would run normally but just much slower than usual.

SCF convergence should not depend on the CPU you use. The only scenario where it could theoretically matter is when different CPUs or different CPU instructions give extremely small differences behind the decimal mark, and it just so happens that your convergence requires a very large accuracy. But this is a wild guess on my behalf and even when correct probably a one in a billion chance. So, I think a mismatch should not have an effect on convergence.

Are you experiencing such problems?

Kind regards,

On Thu Mar 13 '14 4:41pm, Yura Vishnevskiy wrote
>Hi All,
>I know, I should use Firefly version optimized for my type of CPU. Nevertheless, I'm just curious to know, is it normal and expected that SCF does not converge when my CPU and Firefly version mismatch?

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