Different return from get_dtheta and get_dtheta_regular function for asymmetrically cut crystal

[wholingfei]

Hi,

I am not sure whether there is any misunderstanding from my side about the "get_dtheta" function and "get_dtheta_regular" function for asymmetrically cut crystal. They give different values when I set the same crystal. My simple example is Si(111), tK=300, rho=2.329, alpha is -3.0 degree, photon energy is 12.4 keV.

I think I am familiar with the equations in "get_dtheta_regular" more than "get_dtheta" function. May I ask where do I get wrong?

Thanks.

[kklmn]

Hi,

The expression for get_dtheta was taken from André Authier's book "Dynamical theory of X-ray diffraction" (ISBN 0-19-855960-7), Eq (8.3). See the comparison between the two expressions in Fig. 8.3.

I will add the reference to the book in our docs.

[wholingfei]

Hi, thanks for the reply! I will have a look at the equations.