### FFT grid in BSE calculation

Posted:

**Wed Oct 11, 2023 9:00 am**Hi everyone,

I did two BSE calculations using a different number of RL's in the screening calculation.

To my surprise the FFT grid changed when I increased the number of RL for the screening.

I thought the FFT grid size is solely related the the number of plane-waves of the wave function.

Can you guide me to the subroutine where yambo decides the FFT grid size and could you explain why it depends on the screening G's?

Thanks a lot in advance.

Best,

Franz

I did two BSE calculations using a different number of RL's in the screening calculation.

To my surprise the FFT grid changed when I increased the number of RL for the screening.

I thought the FFT grid size is solely related the the number of plane-waves of the wave function.

Can you guide me to the subroutine where yambo decides the FFT grid size and could you explain why it depends on the screening G's?

Thanks a lot in advance.

Best,

Franz