scale set scale
maxhkl maximum hkl to be accepted for reflection selection
phi specify reflections to be phased
MEPHAS Option Code
mode of operation ms test 16 centric reflections
mo oscillate prior centric reflections1
mc x step refl by x degr. 11<x<181 22.5
mf fit general reflections
maximum reflections nr n treat n reflections 16
maximum iterations it n iter per phase trial 1<n<36 13
convergence factor cv x stop when σ()*cv |-| 1.0
extend ms checking ex max 256 trials
entropy weight factor wt x used to select best phase set2 1.0
phi starting phases up use bdf phase values in phi line
reflection discard df x discard refl3 if Δ(F) < x 1.0
data set number ds n 1
print input reflections pr n print n lines of reflections 0
σ as fraction of si x used if σF is not on bdf 0.05
use xx1 prior map pi automatic for very large maps
use xx2 corr map ci automatic for very large maps
use xx3 rev Fourier ff automatic for very large maps
centric phase threshold th x min4 for phase to be centric 0.01
check correlation cr n n refl used to check corr of 0
min value of cf x min allowed in corr survey 0.1
pixel threshold ro x set pixels in input map 0.00001
non-MEDENS map nm med not prepared by MEDENS7
1 Requires phi input lines to specify reflections, and may not be run ab initio.
2 Criterion = wt*ENTROPY+( 1.0-wt)*CORRELATION. See option cr for causing correlation of unphased reflections to be calculated.
3 In cycling modes Δf=(-). In fitting mode Δf=*(-)
4 For values of cos or sin below this value the angle is set to nearest 0/90/180/270 value. Value must be between 0.00001 and 0.2
5 The n largest values will be selected up to a maximum of 1000. The cr option takes precedence if this value is set low.
6 Protects against zero and negative values in non-MEDENS maps.
7 Causes a preliminary scan of the med file to establish ln() and ln(). Uses the ro threshold to screen against holes.
scale 1 scale factor
2 scale group number
maxhkl 1-3 maximum |h|, |k|, |l| for automatic selection of reflections to be fitted and to protect for map resolution limitations
phi 1-3 h, k, l
4 φ in degrees
This field is optional. If left void the value used will be taken from the input bdf unless the up option has been used in the MEPHAS line. If the phase in the bdf is undetermined or the up option has been specified, the phase will be set to zero for general reflections, or to the lower value of the restricted centric phase as is appropriate.