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user-friendly
program can be dowdoadcd
lbr the "cost" of
yoü modem
time, and it will off€r many teäturcs
not even
found in comnercial Packäges
I $ä1. ro
rhdnk t\e
!trhor\'or
lherr
reddne*
ro
gi\e a
brief description
of their progräm. and
I encourage
other
au-
thors of sofrware^Veb
pages/manuah
etc io follow their €x-
ample.
To keep üis section
ful] of life and up-to-date,
your
inpul is absoiutely
necessary
Besl
wishes,
Robert
E. Dinnebie.
Laboratory
of Crystallography
Univ€rsity
of Bayrcoth
D 954-40
Bayreutlr
Gernany
E nail: roben.dinnebier@uni-bayreuth.de
Powdercell
2.0
for windows
G. Nolze & w Klaus, Federal
Institute for Materials
Research and Testing (BAM), Unter den Eichen 87,
D-12205
Berlin,
Gernany,
e:mail:
gert.nolze@bap.de
Abstract
Po$'de{etl .onunr:s
z colnfortable,
user
friendlv visual-
izalion and modification tool fo. crystal structures lt plo
vides oniine catcutation
of the corresponding
powder dif
fraction patterns simulating a variety of experimental
conditions.
The common
ICSD änd Shelx {ile lotmats are
,upponed lor rmporung
Lrliul strucldre
inlormrrion
ll ha'
co;nol ol auromäric
cell rranifoßtralion
and al\o deri!Jlion
of subgroups.
More thän 740 different settings
of the 230
5pare-grout
'ype5
siU be
rupponeJ
Uo lo len
crlslal
\ruc-
Lures can be
considcred
.itruluneou\l)
A lull
panem ßnoe
menl enables
the direct comparison
with experimental
dil-
fractogams
for quantitative
phase analysis'
lattice parämeter
refinemenl,
polynomial background
estimaion' etc-
Key words: refinemenl,
subgroups,
unit cell transforma-
rion, quantitative
phase
analysrs,
stnrcture
vlewer
l. lntroduction
Po d€det represenls
the dircct successor
of the DOS
prosram
POWDER
CELL (Kraus & Nolze,
1996).
even
ihoueh
it was not a sinple conversion
to the windows envi
ronrnent
usine
Borland's
Delphj
l 0 Using
Microsofi
win-
dows
has some
significant
advantages.
Tbe most important
is
the indeDendence
of speciäl
hardware
adaplatrons
such as
ootimal icreen resolution
or existing
printer d'ivers The use
ri rhe
.lrpborrLl
oaen
a comronJble
po'rbili'v for sinple
,.1ps11
,,. r...u11.
lprcrure,.
oalr.
erc
I
inlo olli(e
appLcali,,n..
runheimore. *uitiple .t u"tu." processing
is implemenled
with the ability
to produce a theoretical
mixture
of up
lo 10
seemingly
small details
were considered
during
the
planning stage. for €xalnple,
different
oxidation
states of a
eiven element in one and the same
crystal structure
can be
Aefned by diffetent properties,
e g.. alomic scattering
fac'
256 Powder Difir.,
vol.
13, No
4, December
1998
toIS. colors: either the powdef pattem simulation or the crys
tal slructure
drawing may be switched
off if desired These
considerations led to a principle .econstruction of the code,
while the aim of the program was rehined: the suppolt ot
crvstal anrlvsis b! the intuilive creätion of structure nlodels'
rn'"nnt.ost lo ueriion 1.0. the second
release
is charactenzed
bv e6\ Io-handle
rehnemerr
\ d a Gruptucal
U'er Inle'{ace
rfre'mponarr
teature'
ol qhrch
ale
de'cnbed
belo$
ll. Crystal
Structure
Generation
and
Manipulation
The st uctüe data
imporl has been exlended
in PovdT '
Cel. In additional !o lhe POWDER CBl-]-'specilic jnitial
data {iles (with erlension + cel), ICSD and SHELX files
(*.txt and
*.res
extensions
respectively)
can be imported For
üe ICSD
impon
rn aulomalic
unil
cell lran'for'nation
pro-
cedwe is implemented
since many crystal srmcturcs arc
aiven in non-conventional
settings.
However,
the cell trans-
iormation procedure
is appljcable
in anv other case
where a
nonconventional
choice of basis
vectors
has been used for
üe description
of the unit celt. The program distinguishes
between
more than 740 different settings
of üe 230 space
gmup types. The transformation
procedurc fot nonocljnic,
onhorhombic,
and rhombohe&a1
space-goup
types constd-
ers a pelmulation or superposition
of basis
vectors An addi_
tional shift of all atomic coordinätes
in the asymmetnc
umt
allows settings
where
rhe
new basis
veciors are
chamcterized
by a new origin (necessa./ for some
monoclinic
se$ings) ln
contrast.
the SI{ELX converter
transforms
the glven sy1nme-
try operatols
inlo a predefined setting
ofÄpace_group
types
This is necessary
because
of the setting
sensitjve
extmcton
Ialus used
h Powde{e . Figure 1 shows
the implemerted
crystdl structure
editor which can be used
for the input of a
new data set or to show and edit imported
crystal slructure
wlereäs in the DOS version. the complete
set
of general
po\flrons wa\ defrned
In üe \ymmery ble lo geremle äll
;rodric
po'irion' $nhin rhe
rtü cell.
Poüetcell 2.0 a2plie'
the generätors listed in the Intemätionäl
Tables
for Crystal-
logaphy (IT) (Hann,
1995) This fact means that the genera-
rion p.ocedure derives
the general or special
posltons re-
Fieur L cry$al *ru.rurc data crn b€ edited in ! very simple N2v. Add'
tioml inbrmalion can b. added as a coment
lrtemariona
Bepons 256
quired, üsing eirher aU or a subser
ol rhe posrrron-retated
generJlor\.
One
udvdnrage
of
lhi. pro,edure
is
,he
&c,"r.ed
odrd
'or
ezcn
rerrjog given
;n
lhe
.)
mmer)
hle pcq
spgr.dor.
Alco. the pu.sibiliry
of ryping
enor. h \er) \ma which
b
rmpodant.
cunsidering
rhe
polen
al] trrge
number
of \et_
rng\. rünhermore.
il decredses
lbe
run rime
and
enäbles
üe
user
to undersrand
and check
the locat syrnmetry
of special
^ Regffding skucture
modeling,
one of the most interest
n8, 'eature\
i\ 'he fu y auromäric
generar;on
of.ubgroups
and
(panidlly) .upergoupc.
Ttus
feature
offeN
a con orrable
derivaloo
of cubgroup,
b' sradual
decred\e
or,)mmery
1as. ror rhe de.cnprion of crysLauog,aphir
phase
Ijansrtron.t.
see
Figure
). the
ddu used
are an
exrraclron
oI
:: !.ctj
.".q
^T !h: tompreret)
denved
and l?butared
b] U.
Muler {19q4)
I .ing rhe.e
dara.
üe prog|am
catcutale\
rhe
ne$
Dasß \ec,or\.
u-arclorms
äll alomic po.irion..
and
detel
mlnes
me asymmerfic
unit in reiation
ro ihe new space group
symnetry. Additiomly. the Wyckoff positions
are identined
rn .one.\pondence
ro lho,e g'ven in üe IT. All e(i.rjng
wlcLofi posrüons
hä\e been classified.
As menüoned
ubole.
lhe,)nmeLry dependenl
Wyckofi ,olarion
$i be
useo
ror sere(_Lrte
generadon
of üe atonxc posirioo,.
The
oenveo
crysral \trucrure
parajnelerr
can be
€dited
dd sa\ed
rn änalog)
to u.uät
"üucrure
darä ra\ in Figüre
, we sanr
ro poinr
our tiar in rhe progam
a u\er_fäendly
oel'tce ex$ts ro manipulate
crystal srructures,
onty by ro;
tron and transtation
of atoms.
Therefore,
rhe desired
atoms
must
be selected
before
using
difierenr tools.
The aroms
wlx
FieüE 2. The po$ibte naxin2r subsronps
of a gild
space group qpe can be selated ea\jly.
be
displayeJ
b) harcbng
'.ee
Frgure
l). For
rhe maniputr
rion
thal
lbliou..
rhe
Drogrrm
reduce\
lhe.etecred
om, ro
lho.e
in
lhe
a.)mmeLnc
unir.
i.e..
ontJ
üe dronxc
p,biLron\
or $e ,,) orJnernc
unir s;ll be changed.
The ,ynmero of üe
crysral
$t be
consened.
.Powdet(e enable,
'ülarior, atong
lhe bä5r5 \eclors
and
also
aloog
a predeijned
düeclion
bel$een
lso aromic
posrtions,
i.e., a bond.
The rotarion
is carried
out arorind
rhe
center
of graviry,
a predefined
atom,
or a vecror given by the
l$o dlonlc
po.ir;un\
fFi$re lj. Airer
nänipuldri.n
lhe;n-
nueoce
oo
rhe
calculated
po$der
pä em cän
be ünmedrdrely
srudied.
__. The cryslal srrucrure
rcpresenration
can be eiponeo as a
Windows
Meta
Fite (*.wmf),
as a posrscript
fite, or as
a
POVRä)
,cripr.
fhe la e. i\ e,pec,ajtJ
"urraLle
for rhe
cre
alion
of pboto
realislic piclure.
b) üe u\e ol pOVRay.
a
ree$are
raylrar
Ing progTdm ravaitabte
är $wk.porm).orgr.
lll. Powder
Pattern
and Retinement
In conrasr
ro rhe
DOS
version,
powierce[ 2.0 is able
to
simulale
nor only X ray panems
but also neurror difftaclion
pattems_
Arnong
orher
things,
the influence
of a variable
pri_
mary sür .]srem hä' been
cor\rdered.
the seneralron ol
equivulenr
Debye
Wa er tä,ror,
r.rng r}e coni.pondng
an_
'$ffoprc component\
gilen rn üe |CSD ha5
been
rtnpte-
menreJ.
dnd
üe $eI+nown
p,eudo_
Vo ig1 pron
te runcrron
i.
ävarlable
ro
describe
üe reflecuon
prohte\.
funh(more. ,r
r.
FiguE:1. The crysrd stücture is Epresenred
by tne cont€ni
or hr trlmeb. urur Tbe
Dnr ce e,lges
m trdcd
uur.
r he hJlc,ted
pan
of thc
AJmeLnc untr
ua be
rcrired
$
Powder
Dtffr., Vot. 13,
No.4,
December
1998
liielrc.1. Thc scrco duDp shows i rypr
c.i aüangenent conr.rnmg rwo crlnlr
{rrrurer and
rhe corestonding ponder
diffra.noi taden. The di1Lrcn.c.une
sho*s thc lood agr.Dc betweer n.x
ruEd and Enned poqder prlrenr.
possible
lo enlafge rhe
paLtem
lo tirll screer. a lunction oftcn
requested
in the DOS version.
| , r'ts r\. . d\a n:ree. oi w:r!1.
$.. rhr pr^ts a r. i. .u r-
able
for rhc calcularion of powder paLlcms of phase
nixtures
ll-igure .1).
Thc da$,ing possibilities hälc bccn extended to
alkrw üe cokrrs ol points
or lines
to bc ser by the user. Ody
tlrc differerlt crystal slfucture dai! nlusl be loaded to get
the
resulting po\lder panem. Thc sum as well as the single
..I\' , .. r be .l plJrel I Jhrl n. ol relecr:o.r. roJ il
cludes Nliller nolation. lt{iller-Bravais notalion. d values.
Brngg nngle\. strucLure
anplitudes. integral ini.nsitics, and
FwHNl. Addition.rlly a lisling of ail reflections combined
$ith a line
cuhor allo$,s an eas) identilicttlo! in the
po\)"der
Another new Lature is the implementation of a full pat-
|em refinement
procedure
to optimjze selected
parameters
using the Marquard aleorithm.
Allhough the Marquard algo
dthm {see
for examplc
Young. 1995) is rclatively
slow and
needs a nininum of I itcrrtions fo. convergence.
the con
vergence is -cenerally
morc st.rble. The proeram
rcfines
back
ground,
lattice
t{ramctcrs, FI'HM in dcpcndence of 24 i!
tcnsity scalc facror, deg.ee of pre-setected prefened
o.ientalion,
7e.o shift, and samplc displacemcnl
(\cc Figurc
5). Rcfincmcnt of .{omic positions
has not
)el been included.
Once convergence has been ßached. all parameters
can be
retined simultaneously. Thus, a phase
mirture can be ana-
lyzed
quandtatively
without any inlernai or external standrrd
if the cryslal sructures of all phases
are known. The raw
Figtrrö 5 Relinible td mete6 c$ be switched on oroL
tnr ca.h cLynal i0ctrri..
258 Powder Diilf, Vol. l3 Nc. ,1 Decenber 19sB IntemalionalRepots 258
powder can be loaded in several different file formats includ-
ing Siemens, Philips, Sietronics CPI and XY (angle, inten-
sity) format. The optional display of the difference plot and
the agreement factors supports the goodness-of-fit visually.
A message box shows important R-values during the refine-
ment process. A comparison of R-values before and after the
refinement is possible on the result screen. The diagrams can
be saved or exported in *.wmf format using the Windows
clipboard.
PowderCell is free of charge and can be downloaded
from the following Web site:
http://www.bam.de/a_v/v_l/powder/e_cell.html
The program, all essential data, and some example files of
crystal structures are included in the compressed file. Be-
cause of the intensive calculations during refinement, a PC
with Pentium CPU is recommended.
Acknowledgments
The authors wish to thank U. Miiller for his cooperation
with regard to the implementation of subgroups. Further-
more, we are grateful to R. Allmann, L. Cranswick, and B.
Miiller for inspired discussions and to all users who helped
us in debugging the program.
Hahn, T. (1995). International Tables for Crystallography Volume A -
Space group symmetry (Kluver Academic Publisher, Dordrecht/Boston/
London).
Kraus, W., and Nolze, G. (1996). "POWDERCELL - a program for the
representation and manipulation of crystal structures and calculation of
the X-ray powder pattern," J. Appl. Crystallogr. 29, 301-302.
Miiller, U. (1994). "Relations between Wyckoff positions among crystallo-
graphic group-subgroup relations," Suppl. Issue No. 8, XV. European
Crystallographic Meeting, Dresden, 28. August-2. September, Book of
Abstracts, Z. Krist., 203.
Young, R. A. (1995). IUCr Monographs on Crystallography: The Rietveld
Method (Oxford University Press, Oxford), 3rd ed.
Calendar of Meetings
Donald R. Petersen
Greenleaf Associates
6210 Siebert Street
Midland, MI 48640-2724
23-29 January 1999
23rd Annual Conference on Composites, Advanced Ce-
ramics, Materials and Structures. Cocoa Beach, Florida,
USA. [Contact: American Ceramic Society, Post Office Box
6136,
Westerville, OH 43086-6136, USA. Fax:
1.614.794.5882; E-mail: customersrvc@acers.org; Info:
http://www.acers.org].
8-12 February 1999
AXAA99 Eleventh National Workshops and Conference
of the Australian X-ray Analytical Association: Analyti-
cal X-rays for Industry and Science. Parkville (near Mel-
bourne) Victoria, Australia. Held at the Victorian College of
Pharmacy. Emphasis on XRD, XRF, and X-ray surface
analysis. February 8-9 devoted to workshops, February
10-12 to the conference proper. [Contact: Dr. Mick Gould,
13 Jeffrey Street, Mt. Waverley, Vic. 3149, Australia. Tel:
61.3.9887.8003;
Fax: 61.3.9887.8773; E-mail:
ca@netwide.com.au; Info: http://www.latrobe.edu.au/www/
axaa].
28 February-4 March 1999
128th Annual Meeting and Exhibition: The Minerals,
Metals and Materials Society (TMS). San Diego, Califor-
nia, USA. [Contact: TMS, 420 Commonwealth Drive, War-
rendale, PA 15086-7514, USA. Tel: 1.724.776.9000; Fax:
1.724.776.3770; E-mail: tmsgeneral@tms.org; Info: http://
www.tms.org].
8-10 March 1999
7. Jahrestagung der Deutschen Gesellschaft fur Kristal-
lographie. Leipzig, Germany. [Contact: Frauen B. Kahnt, H.
Schwarzer, Universitat Leipzig, Institut fur Mineralogie, Kri-
stallographie, und Materialwissenschaft, Scharnhorststrasse
20,
D-04275 Leipzig, Germany. Tel: 49.341.973.6250; Fax:
49.341.973.6299; E-mail: dgk99@rz.uni-leipzig.de; Info:
http://www.uni-leipzig.de].
15-19 March 1999
International Centre for Diffraction Data, Spring Meet-
ing. Newtown Square, Pennsylvania, USA. Annual member-
ship meeting. [Contact: Linda Shertz, International Centre
for Diffraction Data, 12 Campus Boulevard, Newtown
Square, PA 19073-3273, USA. Tel: 1.610.325.9814; Fax:
1.610.325.9823; E-mail: shertz@icdd.com; Info: http://
www.icdd.com].
259 Powder Diffr., Vol. 13, No. 4, December 1998International Reports 259
http://dx.doi.org/10.1017/S0885715600020856
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