ABS (CCP4: Supported Program)

NAME

abs -  A program to determine the absolute configuration (hand) of the heavy atom substructure and calculate an FOM.

Source Code

abs.f (SHIFT click to save on disk)
To compile: f77 -o abs abs.f -L$CCP4_LIB -lccp4
On a Linux box, use: f77 -o abs -static -fno-second-underscore -fno-globals abs.f -L$CCP4_LIB -lccp4

SYNOPSIS

abs hklin foo_in.mtz
[Key-worded input]

DESCRIPTION

ABS is a program to determine the absolute configuration (hand) of the heavy atom substructure or polar space group using anomalous scattering. It also calculates a figure of merit which is a useful assessment of the heavy atom substructure. The algorithm is based on the Ps function method (Woolfson & Yao, 1994 and Hao & Woolfson, 1989).

INPUT AND OUTPUT FILES

Input

HKLIN

(compulsary)

Input MTZ file. This should contain the conventional (CCP4) asymmetric unit of data (preferably from TRUNCATE). See the LABIN keyword for columns used.

Output

Results are shown in the log file.

KEYWORDED INPUT

The various data control lines are identified by keywords. Only the first 4 characters of a keyword are significant. The cards can be in any order. Numbers in [ ] are optional and can be left out. The available keywords are:

TITLE <title string>

Upto 80 character title.

LABIN F=...  SIGF=...  DANO=...  SIGDANO=...

(Compulsory.)
F: mean F magnitude.
SIGF: standard deviation of F.
DANO: Friedel difference. Must be column type D.
SIGDANO: standard deviation of F2.

RESOLUTION <rmin>

High resolution cutoff in Angstrom (default value = 4).

ATOM <x> <y> <z> [<occupancy>]

(compulsory)
Fractional coordinates of anomalous scatterer(s).

PRINTER OUTPUT

Results are shown in the log file.

EXAMPLES

Unix example script

• abs_ompdc.com  (SHIFT click to save on disk)
• ompdc.mtz (test data,  SHIFT click to save on disk))

REFERENCE

Hao, Q. (2004) J. Appl. Cryst. 37, 498-499. “ABS: a program to determine absolute configuration and evaluate anomalous scatterer substructure”.

AUTHOR

Quan Hao, Cornell University.