\chapter OVERVIEW

The Powder Suite package of computer programs is designed for interactive 
and limited batch processing of powder diffraction data. The package 
consists of several programs, which are briefly discussed in this chapter, 
and in more detail in a chapter devoted to each program. Also discussed
here are features that are used all programs.

\subrub Organization of Programs

The programs used in this package all have the same type of internal
organization, modeled after the command structure of the VAX/VMS DCL
command language. Once the program is started, any appropriate 
command for that program may be entered, usually in any sequence. 
The format for a command is:\par
|       COMMAND[/qualifiers] [parameters]|\par
or\par
|       COMMAND [parameters][/qualifiers]|\par
(the |[ ]| symbols are used to indicate that an option need not be specified.)
If it is desired to spread a command over several lines, end all but the
last line with a dash (|-|).

For most commands, it is possible to achieve the same results by 
specifying command with no qualifiers or parameters and the program 
will prompt for important options (prompt -- meaning the computer will 
request input). It is often faster to specify options on the command 
line. However, some infrequently used options on certain commands are 
only available on the command line.

For example, in program CMPR, a file may be plotted by typing\par
|        PLOT|\par
this causes the program to prompt for file number(s) and some scaling 
information. Typing\par
|        PLOT 1/XLOW=10/XHIGH=40|\par
Causes file 1 to be plotted from 10 to 40 degrees. The |/TITLE| option,
which puts the file's title on the plot can only be requested with a 
qualifier. To get a title on a plot type one must enter\par
|        PLOT/TITLE    | or\par
|        PLOT 1/XLOW=10/XHIGH=40/TITLE|\par
Programs which offer a |DEFAULT| command have two modes AUTO and MANUAL. 
In AUTO mode the program will use default values for options wherever
possible. However, if an option is specified on a command line, the 
command line specification overrides the default.

At this time, not all options within a command may be specified 
on the same line as a command, but this will be changed in later 
versions of the package to allow those commands to be used in batch mode. 

\subrub Description of Programs

A brief description of the programs currently contained in the package
follows. Complete documentation of the commands available in each program
may be found in a following chapters.

\subsubrub Program LOGIC

Program LOGIC locates entries in the JCPDS-ICDD data base either from a 
JCPDS-ICDD entry number or by searching the database for compounds matching 
a specified chemical composition, chemical/mineral name or with peaks
in selected regions.
The program can display or print 
relative intensities versus \twotheta\ or d-spacings for the selected entries,
or plot the same data, optionally displaying an experimentally determined
powder diffraction pattern or set of peaks on the same scale.
LOGIC may also be used to examine lists of matching patterns determined
by program SEARCH. Experimentally determined peak positions may be read 
from the SEARCH parameter file for graphic display along with the
matching patterns.

\subsubrub Program SEARCH

Program SEARCH is used to search the JCPDS-ICDD database to identify
unknown phases in patterns. Peaks may be input directly to 
SEARCH, or can be read from a data file written by MANIP. 
Chemistry requirements may be used to limit the number of entries
that must be examined by using the LOGIC program, which may be 
called from within SEARCH.
Use of chemistry also reduces the number of spurious matching
patterns by eliminate from consideration materials with 
unlikely compositions.
Depending on the number of entries to be examined, the 
database search may require anywhere from seconds to several minutes 
of computer time, so the user has been given the option to execute the
search either interactively, or with a batch job -- freeing the terminal 
for other uses.
SEARCH writes a file of parameters which may be reread and 
modified in a later SEARCH run. 

\subsubrub Program CMPR

Program CMPR is used for comparison of diffractograms. Data may
be plotted, added, subtracted, and/or compared to JCPDS-ICDD entries. 
This program is still under development.

\subsubrub Program MANIP 

Program MANIP is used for processing of a single 
diffractogram. Operations that may be performed include 
baseline assignment and stripping, \Kalpha2\ stripping, 
interpolation, smoothing and peak processing.
This program is still under development.

\subsubrub Program ENCODE

Program ENCODE is actually a sequence of four programs which create the
files needed by Powder Suite from the full (PDF-2) JCPDS-ICDD database.

The first program, PDF1, reads the PDF-2 database and creates a condensed 
subset of the original database called the PDF-1 database. These
entries may also be indexed by the PDF1 program and will be accessible 
by the other Powder Suite programs. Optionally users may add their own
PDF-2 entries to the database using this program.

The second program, ADDPDF1, is used to add PDF-1 format entries to the 
PDF-1 files written by program PDF1. These entries are easier to prepare
than PDF-2 entries. Use of this program is optional.

The third program, WRDI, is used to create the d-space index files 
which are used for rapid searching of the database by peak position.

The fourth program, WRCHEM, is used to create the elemental composition 
index files which are used for rapid searching of the database by 
chemistry.

\! \input local

\subrub DCL Command Procedure

The VAX/VMS operating system provides a subdirectory structure 
that allows users to catalog their datafiles by storing them 
in different subdirectories. While fully-specified file names may be 
input for file names to the Powder Suite programs, it is usually most 
convienient to use the name without a device, directory and extension.
In this case, most files will be written in the current default directory
with an extension selected by the program. (Certain temporary files 
will be written in a designated scratch directory, |PS_TMP:|). 
It is suggested that users of these programs periodically ``clean-up'' 
(delete unneeded files from) their working and scratch directories.
The clean-up process is easier if several subdirectories and 
descriptive file names are used so that junk may be discerned from 
still-needed information. If the user creates a subdirectory for 
each project and sets current default (using the DCL |SET DEFAULT| 
command, or the equivalent) to the appropriate subdirectory before 
using the PS package, all files for that project will be placed in 
that subdirectory.

To aid in using the Powder Suite package from a directory or disk 
other than where the programs are stored, a command procedure named
|PS.COM| defines the required logical names and symbols. Typing\par
\TAB {}  |$ @dev:[dir.PS]PS|\par
where |dev:[dir.PS]| is the location of the Powder Suite files,
starts a menu where a user can access the programs or get help 
information. After the first time the procedure is called, 
a symbol |PS| is defined which is equivalent to the above command, 
so typing |PS| will also start the package.
For convenience the symbol PS may be defined as\par
\TAB {}  |$ PS    :==   @dev:[dir]PS|\par
in the user's or system login file and the user never needs to use the
initial |@dev:[dir.PS]PS| command. (An alternative to this is to place 
the command\par
\TAB {}  |$ @dev:[dir]PS INIT num|\par
in the user's |LOGIN.COM| file; this defines a terminal type as |num|,
(see the Customization Instructions).

To run a specific command, it is possible to bypass the menu, by typing\par
\TAB {}  |$ PS command|\par
for example, |PS LOGIC| or even |PS L| to start program LOGIC.
Note that program names can be abbreviated down to 
any unique abbreviation (eg. |C| for CMPR). 

The first time the |PS.COM| procedure is called, a second file,
|PS_INIT.COM|, is also executed which defines all of the symbols 
and logical names required by the package. When the package is
first installed, the |PS_INIT.COM| should be updated to reflect
the local computer environment (device names etc.)

In addition each user can have one or more customized |PS_LOCALINIT.COM| 
files. 
The following locations are searched (in the order specified) 
for the |PS_LOCALINIT.COM| file:
\TAB 
	(1) the current default directory
\TAB 
	(2) the current login directory (as defined by |SYS$LOGIN|).

In this way, by placing |PS_LOCALINIT.COM| files in different 
locations, differing sets of logical names may be used by 
different users or even for different projects.
The package may be reinitialized at any time by typing 
\TAB {} |PS INIT|\par
The symbols and logical names defined in the |PS_INIT.COM| file
are discussed in more detail 
\! in the Customization Instructions chapter at the end of this manual or 
in ASCII file |CUSTOMIZE.DOC|, which is distributed with the package.

The installation procedure can be used to create the
|PS.COM| and |PS_INIT.COM| files with definitions suitable for the system
where the programs have been installed.
This is discussed in more detail 
\! in the Installation Instructions chapter at the end of this manual or 
in ASCII file |1README.1ST|, which is distributed with the package.

\subrub On-line Help Information

The programs documented here all have VAX help files which may be
accessed either from inside the program or directly from the |PS.COM|
procedure using the |HELP| option. The help information is quite similar 
to the text of this manual. 

From inside a program, type the |HELP| command
to access the help menu. The options for which further information is 
available will be listed following help text. For example, inside program
LOGIC, at the |LOGIC>| prompt, type |HELP| to access the help file. A list
of commands will be displayed. Then type (for example) |MATCH| for information
on the MATCH command. There are several sub-options within MATCH, which can
then be examined. To return to the program press the control key and the 
Z key at the same time (this action is usually called a control-Z 
sequence and is will be abbreviated as |^Z|).

From the |PS.COM| procedure, first type |HELP| and then ask for the 
specific help library by typing, for example, |@LOGIC|. From this point, 
help is available as described above.
