SIMREF

Features:

• Refinement of
• multiple phases
• multiple data sets from X-ray (tubes), synchrotron and neutron diffractometers
• modulated structures with symmetry adapted displacement vectors
• magnetic structures using magnetic space groups
• full pattern without structure model (program SIMPRO)
• Calculation of
• powder pattern
• structure factors
• reflection lists
• Lorentz polarisation and geometry factors for different diffractometers.
• Different peak shape functions.
• Peak-shift correction by fitting a second-order polynomial in 2theta.
• Scaling the 2theta values on standards: the lattice constants of silicon in the whole temperature range up to 1500 K are built in.
• Background fitting with a 6th-order polynomial or fixed values.
• Individual weight scheme for each data set.
• The standard uncertainty of angular postions can be taken into account (Rebmann et al., 1998).
• The Goodness-of-fit is given by N_sigma (J. Ihringer, 1995).
• Calculation of distances after the refinement.
• Quantitative phase analysis.
• Runs on different Unix systems, VMS, Windows 95/NT and MacOS.

New features of version 2.6:

• Asymmetry correction of Bérar et al. (1993) and L.W. Finger (1998).
• 2theta dependent mixing parameter of the pseudo-Voigt peak shape function.
• Preferred orientation correction of W.A. Dollase (1986)

Documentation:

• Brief description of Simref as PDF or postscript file (301kB)

Source code and binaries:

• Source code for Unix and VMS written in Fortran 77 (417kB)
• Binary for Windows 95/NT (599kB)
• Download Simref for MacOS

Diffractometers:

Lorentz polarisation and geometry factors for the following diffractometers are built into the program:

• Guinier diffractometers (reflection and transmission geometry)
• Guinier cameras (film)
• Bragg-Brentano diffractometers
• 3-axes diffractometers at a synchrotron source
• Neutron diffractometers (Debye-Scherrer geometry)

References:

• J.-F. Bérar and G. Baldinozzi, J. Appl. Cryst. 26, 128-129 (1993)
• W.A. Dollase, J. Appl. Cryst. 19, 267--272 (1986)
• L.W. Finger, J. Appl. Cryst. 31, 111 (1998)
• J.K. Maichle, J. Ihringer, W. Prandl, J. Appl. Cryst. 21, 22-27 (1988)
• J. Ihringer, J. Appl. Cryst. 28, 618-619 (1995)
• C. Rebmann, H. Ritter, J. Ihringer, Acta Cryst. A54, 225-231 (1998)

Contact: joerg.ihringer@uni-tuebingen.de