### em1s diagonal elements are not real

Posted:

**Tue Feb 13, 2018 3:00 am**Dear all,

I recently tried to post-process the dielectric matrix, and found that the diagonal elements in .em1s database, which I assumed to be inverse dielectric matrix minus one, has a pretty large imaginary part, in the order of 1% of the real part. If inversed to get the dielectric matrix, the imaginary part is even larger, to 10% of the real part.

To my knowledge the diagonal elements could be real. Is there any transformation I am not aware of, or purely numerical error, or I misunderstood what is in the em1s? Thanks.

Best,

Feng

I recently tried to post-process the dielectric matrix, and found that the diagonal elements in .em1s database, which I assumed to be inverse dielectric matrix minus one, has a pretty large imaginary part, in the order of 1% of the real part. If inversed to get the dielectric matrix, the imaginary part is even larger, to 10% of the real part.

To my knowledge the diagonal elements could be real. Is there any transformation I am not aware of, or purely numerical error, or I misunderstood what is in the em1s? Thanks.

Best,

Feng