Readme.txt for PTST98
release of 26 December 2000

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1. Content

The PTST.ZIP archive contains four files;

PTST98.EXE: the executable program
PTST.IN: example of input file
PTST.OUT: example of output file
README.TXT: this file

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2. Introduction

PTST98 is the revised version of PTST program for the computation of the 
Periodic Intentisity Distribution (PID) of mica polytypes from the model
for the stacking sequence expressed through the RTW symbols.
The program runs under a DOS session in Microsoft(R)Windows(R) and should
run as well on DOS-only machines.
The input file must be named PTST.IN and consists in only three lines. The first line
is a title, a may also be left blank. In the second line the number of layers 
in the polytype period is given. In the third line the RTW (rotational) symbols (one for 
each layer) are listed.
The output file is generated with the name PTST.OUT. It contains three orientatioal 
symbols for the stacking sequence (Zvyagin, OD and Takeda-Sadanaga), the space-group
type, the polytype classification (both reticular and OD) and the PID expressed in the
most suitable axial setting).
PID assumes the all the layers are of M1 type (homo-octahedral approximation), i.e.
that the two orientational vectors for each packet (half-layer) are parallel. In the meso-
and hetero-octahedral families, this may not be the case. Therefore, the orientational
symbols produced in output should be considered an approximation of the "true" stacking
sequence. The latter can be normally obtained only as a result of a complete structure
refinement, but the homo-octahedral stacking sequence obtained by PID analysis represents
a model already very close to the final answer.

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3. Reference

The bibliography reference for the program PTST98 is 

ACTA CRYSTALLOGR. (1998) A54:348-356

Other references for the symbols and settings used by the program are given directly
in the output.


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3. License

The program is distributed free of charge. If you let me know that you have downloaded the file
by writing an email to

nespolo@nirim.go.jp

I shall keep you informed of any future update. You can always visit the WEB site and check for
updates. The download site is linkable without need of any permission.


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4. Feedback

Your comments, bug reports and requests are always welcome.
Considering however that purpose of this program is quite limited, I do not plan to develop
"aestetich" amelioraments like interfaces in the window-style, or versions for other platforms.



Massimo Nespolo
Tsukuba, 26 December 2000
