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You are in luck. I just wadded through all this myself.
The LP correction is calculated and applied in MOSFLM. Scala seems to
want the LP already applied and doesn't seem to have a mechanism for
doing it "again".
The Lorentz factor for the rotation camera geometry is:
1/L = sqrt( sin(2*theta)^2 - zeta^2)
and can be found on page 320 of Blundell and Johnson (1976).
The polarization factor used in MOSFLM appears to be the same as the one
found on page 109 in Drenth (1999):
1/P = 1/2 * (1 + cos(2*theta)^2 - tau * cos(2*psi)^2 * sin(2*theta)^2 )
where:
L is the Lorentz factor
P is the polarization factor
theta is the Bragg angle
zeta is the sin() of the angle between the diffracted ray and the plane
normal to the rotation axis
psi is the angle between the diffracted ray and the electric vector of
the incident beam
tau is the "polarization factor" you put into mosflm (between 1 and -1)
-James Holton
MAD Scientist
wob wrote:
Hi there,
I'm new to CCP4 Program Suite. Could someone please tell me in which
programs are LP corrections applied, and what references are used? I
can't find that information on CCP4 homepage.
Thank you very much for help!
Owen
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