- EPS Internal /
- Support Services /
- Analytical /
- X-Ray Crystallography & Computing Service

- Calculate the coordinates of the centroids X1A and X1B

using CENT/X ATOM NAMES. For X1 these are (*X, Y, Z*) - Calculate the unit vector from B(1) to X1A :- given as (x, y, z)

(NB this is in fractions of unit cell length, and not Angstroms)

by typing LINE X1A B1 - Convert the unit vector to Angstroms: (x/a, y/b, z/c)

where a, b, and c are the unit cell lengths. - Obtain the distance d
_{1}by typing JOIN B1 X1B and then BANG X1B - The coordinates of the dummy atom position D are given by :

(assuming that d_{1}= d_{1}^{'})(X+d

_{1}*x/a, Y+d_{1}*y/b, Z+d_{1}*z/c) - Finally, put the dummy atom in your *.ins file as:
AFIX 1

B12X 3 x y z 10.0000 10.0000

AFIX 0*i.e.*having fixed zero occupancy and temperature factors. Put in HFIX as for closo structures but not including the dummy atom of course!

Links to the other X-Ray Crystallography web pages are also listed here for your convenience:-

Heriot-Watt University

Edinburgh, Scotland, UK EH14 4AS

- © Copyright 2011 School of EPS, Heriot-Watt University
- Disclaimer
- Freedom of Information
- Site maintained by: webperson@eps.hw.ac.uk
- Sitemap