Overall B-Factor Refinement
The xrefin optimize overall statement optimizes
overall isotropic or anisotropic B-factors
by employing a conjugate gradient minimization using
(Eq. 13.1) as the target. For the isotropic
case, the variable is simply the overall B-factor
,
and
in Eq. 13.1 is replaced
by
![\begin{displaymath}
\exp({\frac{-s^2B}{4}}) F_{calc}({\vec h})
\end{displaymath}](img470.png) |
(14.1) |
For the anisotropic case, the variables are the six parameters
of the anisotropic B-factor tensor
, and
in Eq. 13.1 is replaced
by
![\begin{displaymath}
\exp(-2 {\pi}^2 ( \sum_{i=1,3} s_{ii}^2 B_{ii}
+ 2( s_1 s_...
...2} + s_1 s_3 B_{13} + s_2 s_3 B_{23} )
)) F_{calc}({\vec h})
\end{displaymath}](img472.png) |
(14.2) |
Note that
is not touched during this procedure, but it is still
added to the modified
terms to yield
.
After termination,
the procedure multiplies the
structure factors with the
overall B-factor shift. In the isotropic case,
it also adds the refined B-factor shift to the coordinate array Bs.
The
structure factors must be computed
prior to invoking this routine, e.g., through the
UPDAte xrefin statement.
Subsections
Xplor-NIH 2024-06-11