FNO along with single prec

Questions
#1

Hi Team,
Will employing the FNO scheme alongside single precision lead to a twofold increase in speed compared to double precision with the same?
I want to say that can we compare the timings of single precision and double precision along with fno and will it give 2x enhancement of speed ?

Thank you
Manisha

#2

Hi Manisha, these are coupled-cluster FNO calculations, right? The FNO step does not use single precision, but you can still perform single-precision CC calculations that follow. You should see speedups by a factor of approximately two for these single-precision-enabled steps. Just be cautious of the thresholds you use in your calculations; if they are too tight, then the number of iterations may increase, leading to decrease in overall speedups. Please let Q-Chem Support know if there are related concerns.

#3

Thank you @kaushik this is what i am guessing but at that time i was not sure about it .

#4

Manisha, single precision works by conversion of data types and executing contractions in single precision. If your systems are very small, the timings for contractions can become comparable with a simple readout needed for the conversion. To see a speedup, I recommend to look at big enough systems that do not take seconds to run.