SHG error

[Sunxl]

Dear Davide,

I performed additional tests using the fixed version of Lumen.

For the FM system, the problem seems to be fixed. The SHG calculation no longer gives NaN values, and the non-zero (yxx) component obtained with the fixed version of Lumen agrees with the result from Yambo 5.3-master.

However, for the AFM system, the problem is still present. Using the fixed version of Lumen, the non-zero (xxx) component still shows strong positive-negative oscillations between adjacent frequency points, similar to what I observed previously.

Thank you for the reminder. I have added my signature now.

Best,
sunxl