Oh dear - Did you somehow leave off the application of the SCALE
between Fo and Fc in SFALL?
See the GUI
First instruction
Append FC and PHIC to FP .. - then Scale input FP to Fcalc
You have to turn on that radio button..
One common use of this task is to add FC PHIC to several sets of data
and then do difference maps between FPH and FP to find heavy atom sites..
Hence the button
But a better default would be to apply scale automatically if only FP
SIGFP FreeRflag are to be output.
Will amend the GUI to do that..
Eleanor
Harry M. Greenblatt wrote:
BS"D
Dear All,
I addressed this issue to "management" but got no reply.
I wanted to make a map from a published structure, so I downloaded the
structure factors and the coordinates, and used the import facility to
go from mmcif to mtz. Then I ran sfall to generate fcalc and phicalc
from the coordinates. Then fft to make a 2fo-fc map. Looking at the
map in PyMOL and then in coot and contouring at 1.5sigma, it was
obvious that something had gone wrong. While looking in coot, and
pondering what could be wrong, I was idly scrolling the mouse wheel,
which changed the contour. When I got close to zero, the map suddenly
started looking better. Checking the fft output confirmed my
suspicions: the map, instead of going from -0.6 to +1.6, went from
-1.6 to +0.6. Contouring at -1.5sigma gave what one would expect from
a 2fo-fc map. So I guess the map that was calculated was Fc - 2Fo.
I checked the fft output again and confirmed that FP was F1,
whose multiplier, n, was +2.0 and that Fcalc was F2, whose multiplier,
m, was +1.0 and that I had asked for a nF1 - mF2 map.
Perhaps I did something wrong? Perhaps this is a bug in fft?
Thanks,
Harry
-------------------------------------------------------------------------
Harry M. Greenblatt
Staff Scientist
Dept of Structural Biology [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>
Weizmann Institute of Science Phone: 972-8-934-3625
Rehovot, 76100 Facsimile: 972-8-934-4159
Israel
begin:vcard
fn:Eleanor Dodson
n:Dodson;Eleanor
email;internet:[EMAIL PROTECTED]
tel;work:+44 (0) 1904 328259
tel;fax:+44 (0) 1904 328266
tel;home:+44 (0) 1904 424449
version:2.1
end:vcard
