calculation of
Calculation of matrix elementns
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Regarding , it is a linear combination of , so it is not separated into inside or outside of MT for a certain .
For the case where MPB is a function within MT:
: variable name PPB
In the case of IPW:
inside the MT
IPW part
The calculation for the region outside MT is obtained by calculating the MT part and subtracting it:
It should be noted (there might be a Fourier transform factor). . The integral of is written in spherical coordinates because the integration region is a sphere:
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It is also acceptable to expand the plane wave with spherical Bessel functions and consider only the contribution of as the result of the integration.