Question Regarding Surface Mode in ADDA Manual §7

[Manato Koide]

Hello all,

I have a question regarding the use of surface mode as described in §7 of the ADDA manual.

The manual states that when using surface mode, the command -surf <h> {<mre><mim>|inf} should be used, where <h> represents the distance from the flat substrate surface to the center of the particle.

My question is: in the case of an asymmetric particle structure (e.g., a hemisphere), does the "center of the particle" refer to the center of mass of the structure, or is it simply the midpoint along the z-axis of the structure's height?

I would appreciate your clarification on this matter.

Thank you very much.

Sincerely yours,

 Manato Koide

[Maxim Yurkin]

Dear Manato,

As mentioned in Section 6.1 "Reference frames" of the manual, the origin is the center of the computational grid, so
that is the second option from your list. The real center of mass is not used anywhere. If you have any doubts, the
simplest check is to perform a free-space simulation with -store_int_field or similar options. It will produce file with
real coordinates of the dipoles, which can be compared against your expectations. In this coordinate frame the surface
has an equation z=-<h>.

Maxim.