SCIENTIFIC MANUAL
2021
ICSD DATABASEICSD is the world’s largest database forfully determined inorganic structures.
We want to support the community
by offering an indispensable tool formaterials science.

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FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASETABLE OF CONTENTS

GENERAL INFORMATION – INTRODUCTION........................................................ 4
ACCESS OPTIONS...................................................................................................................... 5
WHAT KIND OF STRUCTURES ARE INCLUDED AND SINCE
WHEN?............................................................................................................................................... 7
HOW ARE RELEVANT ARTICLES REVIEWED?.................................................... 10
DATA CURATION...................................................................................................................... 12
STRUCTURE TYPES.................................................................................................................21
EXISTING PUBLICATIONS................................................................................................ 22

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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GENERAL INFORMATION –INTRODUCTION
Find all important inorganic crystal structures
selected and curated from
more than 1.500 scientific journals worldwide

ICSD (Inorganic Crystal Structure Database) is
the world’s largest database for fully determinedinorganic crystal structures. It is made available
to the scientific community and industry by FIZ
Karlsruhe. ICSD contains the crystallographic
data of published crystalline inorganic structures, including atom coordinates, dating back to1913. Organometallic and theoretical structures
have been added within the past years. The ICSD
data are of excellent quality. Only data that havepassed thorough quality checks are included.
As the world’s leading provider of scientific information on inorganic crystal structures, we takefull responsibility for database production, maintenance and quality control, and we ensure that
the ICSD database and our software solutions
meet the highest possible quality standards.
Around 12,000 new structures (inorganic, organometallic and theoretical) are added every year.
Through our continuous quality assurance, existing content is modified and supplemented, andduplicates are removed. As a result, and by filling
gaps from previous years, even the older content

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is not static. A summary of the current release isavailable at https://icsd.products.fiz-karlsruhe.
de/en/about/about-icsd#facts+%26+figures+.

HIGHLIGHTS• Important crystal structure data are available,
including unit cell, space group, complete
atomic parameters, site occupation factors,
Wyckoff sequence, molecular formula andweight, ANX formula, mineral group, etc.
• 80 % of the structures are allocated to morethan 9,000 structure types. This allows forsearches for substance classes.
• Continuous selection and evaluation oftheoretical structures. They can serve as abasis for developing new materials throughdata mining processes.
• Keywords to describe physical and chemical
properties are provided.
• Abstracts for a quick grasp of the article
content are available.
• Simulation of Powder Diffraction Data

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASEACCESS OPTIONSFIZ Karlsruhe provides various options for use of ICSD.

The following ICSD versions are available: ICSD
Web, ICSD Desktop, ICSD Intranet and ICSD API.
All four versions use the same technology: Theinterface runs on a web server (Tomcat), whichruns either at FIZ Karlsruhe (ICSD Web) or at theuser’s site (ICSD Desktop and ICSD Intranet). In
any case, the interface is accessed with a browser. The user-friendly interface is easy to navigate
with up-to-date features:• intuitive search interface• extensive classification in structure types,
which are searchable based on descriptors
defining each structure type• structure standardization for easiercomparison with other structures• extended crystal structure visualization andanalysis tools• powder pattern simulation with the possibilityof enhanced manipulation• simple but powerful query management• direct links to the original literature via
OpenURL server

The data are encrypted and can only be accessed
via the interface or ICSD API.
ICSD WEBICSD Web is a service enabling web access to
ICSD. Its servers run at FIZ Karlsruhe and can beaccessed with a common browser and an appropriate license. Authentication for single users andmultiple users is handled by logins/passwords.
Campus/Site users are authenticated based on
their IP address; in addition, users can create personalized accounts while being IP authenticatedto store searches and preferences. The advantageof the web installation is that you have access tothe database regardless of where you are working.
ICSD DESKTOPICSD Desktop is a Windows-based solution for
individual users as well as small research groups
that would like to install ICSD locally on their
computer/laptop. The advantage of a local instal-

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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lation is that you are independent of any network
connection.
ICSD Desktop installs stripped-down servers to
run the required services on the local machine.
Access from other machines is prohibited. The
software as well as the database has to be installed on each computer. Access via a network is
not possible.
ICSD INTRANETICSD Intranet is an in-house solution based on the
ICSD Web technology. It allows users to offer theirown web-based access to ICSD within their university or company. Authentication is performed
via a separate LDAP module, but can also be integrated into an existing LDAP solution.
API LICENSE
For applications with a large demand for structures (e.g. data mining projects) the regular ICSD
licenses to ICSD Web/Desktop/Intranet may not
be optimal, as there are limitations regarding the
CIF export depending on the license. For example,

a Campus license allows the export of a maximumof 20,000 CIF files per year. If more structures areneeded for a project, the ICSD API allows the user
to use unlimited CIF files for the project. With
the API, searches can be performed using an advanced search language.
The API license is personalized and project-bound. To use the API license you need a regular ICSD license. For the use of the API license anadditional agreement between the customer and
FIZ Karlsruhe has to be concluded. The basis forthis agreement is information regarding the users
and the project for which the data is used.
UPDATEThe ICSD is updated twice a year. The updates
take place in the second and fourth quarters. Relevant crystal structures are included as quickly
as possible. However, due to the complex evaluation process and the amount of relevant crystal
structure data, time delays occur and journals areprioritized. Crystal structure data that has alreadybeen recorded is only visible to the customer after
the update has been carried out.

TERMS OF USE FOR THE PRODUCTS

FIZ Karlsruhe’s general terms and conditions for licensing the ICSD are available athttps://icsd.products.fiz-karlsruhe.de/en/support/support#terms+%26+conditions .
The general terms and conditions for the API license area available at:https://icsd.products.fiz-karlsruhe.de/sites/default/files/ICSD/documents/terms/ICSD_API_
License_2019.pdf.

DEPOT CCDC/FIZ KARLSRUHE; DEPOSITING CIF FILES“Access Structures” is a free service provided by CCDC and FIZ Karlsruhe. With this service,customers can deposit, display and access crystal structures. Access Structures is available at:https://www.ccdc.cam.ac.uk/structures/.
The structures deposited in the depot as cif files are not automatically transferred into the ICSD.
Structures can be deposited using the following link:
https://www.ccdc.cam.ac.uk/deposit.

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FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASEWHAT KIND OF STRUCTURES ARE
INCLUDED AND SINCE WHEN?
ICSD contains the following types of crystal structures:
Experimentally determined inorganic structures
Experimentally determined organometallic structures
Theoretically calculated inorganic structures

When crystal structure data from relevant journals are recorded in ICSD, the main focus is on
inorganic crystal structures. The inorganic crystal structure data are selected by reviewing morethan 30 peer-reviewed journals and additionallyby evaluating a search in specialized databases.
Inorganic structures also include metals and intermetallic compounds, which were increasingly
recorded from 2003 onwards. Data were also recorded retroactively. From 2003 onwards, structures containing C-H bonds or C-C bonds werealso included, e.g. compounds with tetramethylammonium were included as well as oxalates.
Recording these structures is a first step leading
to the inclusion of organometallic structures.
EXPERIMENTAL INORGANIC STRUCTURES
As a rule, only completely determined inorganic
structures, i.e., structures for which the atomic
coordinates and all other required crystallographic information are given, are recorded. In addition,
there are two special cases when the cell and theassociated structure type have been determinedin the experiment, but the individual atomic coordinates have not. Provided that the atoms of theassociated structure type are consistently locatedon special positions with exact positions (e.g.,0, 0, 0 or ½, ½, ½), these structures are also recorded as completely determined. However, it canalso happen that the positions of the atoms in a
structure type have degrees of freedom (e.g., 0,y, ½). In this case, the structure is not completely determined, because the y-coordinate was notdetermined experimentally. Such structures canstill be included in ICSD if the number of degrees
of freedom is not too large. The structure is thendefined by the experimental lattice parameters
and the corresponding structure type that provides the missing crystallographic data, and isincluded in ICSD. The missing atomic coordinates
are derived from another structure of the samestructure type, whereby the atomic coordinates
are entered without standard deviation and onlywith three digits after the decimal point.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE7

ORGANOMETALLIC STRUCTURES
Due to the increasing overlap of inorganic chemistry with organic chemistry, the regulations forrecording crystal structures were extended. Thiswas favored by the collaboration with the Cambridge Crystallographic Data Centre (CCDC). Thus,
organometallic crystal structures have also been
included since 2018. The relevance decision regarding the organometallic structures is made exclusively by reviewing a few particularly relevant
ICSD journals. Since a large number of organometallic structures are published annually, some
limiting rules have been set for the relevance decision regarding these structures.

If publications contain several structures, only the
structures containing at least 3 metals/semime-

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The goal is to evaluate organometallic structureswith a large inorganic part for the database. Pureorganic structures will not be included. Pure organic structures include structures that containcarbon and hydrogen and may also contain oxygen, nitrogen, sulfur, phosphorous, chlorine andfluorine.
The organometallic structures to be covered
should contain at least 3 metals/semi-metals. Organometallic structures containing 2 metals canalso be recorded if the inorganic portion is relatively larger than the organic portion due to oxygen, sulfur or nitrogen. This is a borderline case.

tals or 2 metals with a larger inorganic part arerecorded. The other structures are not recorded.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASETHEORETICAL STRUCTURESThe experimental approach is no longer the only
way to discover new compounds and structures.
There are numerous computational methods for
simulating and predicting structures of inorganic
solids, which have produced a large amount oftheoretical crystal structure data. Based on thesedevelopments, theoretically calculated inorganic
crystal structure data have also been included in
the ICSD since 2016. The theoretically calculated
structures are evaluated and included by Dr. Dejan Zagorac , Head of the Laboratory for Theoretical Investigations of Materials at the Institute of
Nuclear Sciences, Vinča, University of Belgrade,and his team.

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HOW ARE RELEVANT ARTICLESREVIEWED?
Finding the long-tail of articles with crystallographic
structure data makes the difference. In ICSD you can findstructures from more than 1.600 journals

To identify relevant articles from literature, articles
from relevant journals are reviewed and additional searches are carried out in databases for scientific literature. The latter mainly serves to findcrystal structures published in journals that do
not cover the core area of ICSD. New publications

LIST OF JOURNALS ON THE HOMEPAGE• List of the 80 most important journals:
https://icsd.products.fiz-karlsruhe.
de/en/about/list-80-most-importantjournals-covered-icsd• Journal list for theoretical structures:https://icsd.products.fiz-karlsruhe.
de/en/about/theoretical-structuresjournal-list

10from major publishers worldwide are also regularly monitored and evaluated. The relevance decision is supported by directly inspecting possibly
relevant structures in the crystal structure datarepository “Access Structures”. This is especiallyhelpful in order to decide which organometallic
structures are relevant. At present, more than 30
journals are checked for relevance this way; allother journals are covered by regular searches in
Chemical Abstracts.
FEEDBACK ON RELEVANT CRYSTALSTRUCTURE DATA
Information on publications with relevant
crystal structures can be sent directly to
icsd@fiz-karlsruhe.de. This can speed up
the recording of the data in ICSD a bit.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASENUMBER OF RELEVANT ARTICLES IN 2020 FOR THE REGULARLY EVALUATED JOURNALSFIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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DATA CURATIONIn the process of adding a structure to the database,a series of tests are run to verify data
integrity and correctness.
Furthermore, the data is enriched withadditional or missing information.

WHAT CHECKS ARE CARRIED OUT ONCETHE CRYSTAL STRUCTURE DATA HAVE BEEN
ENTERED INTO MYICSD?
Published crystal structures are recorded in the
ICSD database “as given in article”. This is in linewith the long-standing objective of the ICSD to“map” the literature. There are no conversions of“unusual” space group setups in particular, sinceauthors often choose an unusual space group toemphasize an important statement in the article.
Users can also view and search for the standardized structure. Both structures (published andstandardized) are available as cif files for download.
The following data are often missing in publications and are generated in addition:
•
•
•
•
•

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Wyckoff Sequence
Pearson Symbol
ANX Formula
AN Formula
Sum formula

•
•
•
•

Structure types
Standardized data
Density
Atom distance

We include the measured densities (if the information is available) and compare the measured
with the calculated values.
The program also checks the following data:
•
•
•
•
•
•

Sum formula
Oxidation numbers
Charges
Space group
R values
Isotropic and anisotropic temperaturefunctions
AUTOMATIC PLAUSIBILITY CHECKS

The plausibility of the space group is checked. If
there are discrepancies, a corresponding note isinserted automatically in the database.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

If R value, isotropic and anisotropic temperaturefactors are not available, then a corresponding
comment is generated, which is then also visible
in the database. Likewise, a comment is generated if the values are not within plausible limits.
The list below summarizes the automatically generated comments:
Deviation of the nominal from refined formula tolerable.
Deviation of the charge sum from zero tolerable.
Deviation of calculated from measured density tolerable.
No R value given in paper.
At least one temperature is implausible or meaninglessAt least one temperature factor missing in the paper.
A site occupation is implausible or meaningless
Deviation of lattice parameters from crystal system tolerable

STRUCTURE FORMULAE

ANISOTROPE DISPLACEMENT PARAMETERS

For the inorganic crystal structure data, the structural formulas are structured and the charge sums
are checked for agreement. The program defines
a standard oxidation number for the different
elements, but this can be individually adjusted
at any time. In isolated cases, the hydrogens or
water of crystallization in the structure under investigation are not determined or are determined
incompletely. This has the consequence that thenominal sum formula (given by the author) andthe calculated (“refined”) sum formula differ fromeach other, and as a consequence also the charge
sums are not balanced. In this case, “dummy atoms” are inserted to equalize the stoichiometries
between nominal and refined formula.

Anisotropic displacement parameters are given in
one of the following three different forms:
1. ß(max 8 characters)exp(−(h2ß11 + k2 ß22 + l2 ß33 + 2hk ß12 +2hl ß13 + 2kl ß23))
with standard deviations if given.
2. B (max 8 characters each)exp(-1/4(h2B11a*2 + k2B22b*2 + l2B33c*2 +hkB12a*b* + klB23b*c* + hlB13a*c*))with standard deviations if given.
3. U (max 8 characters each)exp(-2π²(h2U11a*2 + k2U22b*2 + l2U33c*2 +2hkU12a*b* + 2klU23b*c* + 2hlU13a*c*))with standard deviations if given.

With organometallic crystal structure data, themolecular formulae are not structured, due to thecomplexity of the chemical composition. Also, theoxidation numbers of the individual elements are
set to 0, whereby a formal balance of the charge
sums is always achieved.

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GROSSULAR | COLLECTION CODE (CC) 24946

CRYSTAL STRUCTURE DATA OF A GARNET STRUCTURE CALLED GROSSULAR WITH THE COLLECTION CODE (CC) 24946 COPIED FROM ICSD.

CRYSTAL STRUCTURE OF GROSSULAR (CC24946)

GROSSULAR, PHOTO: ROB LAVINSKY, IROCKS.COM
https://de.wikipedia.org/wiki/Grossular#/media/Datei:Grossular-137781.jpg

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FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASEDOLOMITE | COLLECTION CODE (CC) 10404

CRYSTAL STRUCTURE DATA OF A CARBONATE STRUCTURE CALLED DOLOMITE WITH THE COLLECTION CODE (CC) 10404 COPIED FROM ICSD

CRYSTAL STRUCTURE OF DOLOMITE (CC10404)

DOLOMITE (WHITE) AND MAGNESITE, PHOTO: DIDIER DESCOUENS
https://de.wikipedia.org/wiki/Dolomit_(Mineral)#/media/Datei:Dolomite-Magn%C3%A9site-_Navarre.jpg

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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OXIDATION STATESFrom the atomic coordinates the program calculates a sum formula, which should agree with theentered sum formula. With inorganic entries, thesum formula is structured intellectually. If these
two sum formulas do not match, a comment is
automatically generated (see list of comments on
page 13) and inserted.
The oxidation numbers of the elements are assigned automatically. If the positive and negative
charge sums do not match, then the oxidation
numbers of the individual elements are changed
manually.
It is also possible to specify an average oxidation
number for a given element (average charge calculation is triggered), in which case a corresponding comment is generated. In some cases, the hydrogen from the present water is not specified in
the refinement, but in the structural formula. Herethe missing hydrogens can be added. If the positive and negative charges do not match, a corresponding comment will be visible in the databaseat the respective entry.

R VALUES
Of course, the R value can only be specified if it
is quoted in the present publication. The definition of the R value is then entered in the Comment
field. The message “R value is missing” is automatically inserted when the entry is set to productive.
EXAMPLER = R(wp)16

ATOMIC COORDINATES, ISOTROPICDISPLACEMENT PARAMETERS, SITE
OCCUPATION, BONDED H-ATOMS
The atomic coordinates x, y, z are given with amaximum of 7 characters each. The isotropic displacement (temperature) factor is given as “B” if
defined byexp(−B (sin2 θ)/λ2)
or “U” if defined byexp(−8π2U (sin2 θ)/λ2) .
Since 2003 isotropic and anisotropic temperature factors are given if both are available. Older records contain either isotropic or anisotropic
temperature factors (if anisotropic temperaturefactors are available). Displacement factors may
have a maximum of 6 characters. The site occupation (max 5 characters) describes the statisticaloccupation of the site, i. e. the quotient of the actual amount of atoms and the maximum numberof positions of the site. A special remark is generated for defect structures with SOF < 1. They needa special treatment when the Pearson symbol or
the ANX formula is generated (see chapter 4). The
number of undetermined H atoms bonded to another atom (e. g. H bonded to O in H2O, or N in
NH4+ ) is noted.
FEEDBACK ON RECORDED CRYSTALSTRUCTURE DATA
Discrepancies may occur in the recorded crystal structure data despite multiple
checks. Discrepancies include, for example:
errors in writing the article by authors or in recording the structures by FIZ Karlsruhe. They
can be reported to icsd@fiz-karlsruhe.de.
Until the next update, the discrepancies
will be corrected.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

REMARKS
There are standard remarks, free text remarks,
and test remarks that are messages from the test
program. The standard remarks consist of threecharacters. They are searchable and listed below.
Please note that the remarks TEM (temperature inK) and PRE (pressure in MPa) contain numericalvalues and will be made numerically searchable
in future updates. All remarks will be displayed ina full sentence.

TEM Temperature in Kelvin
THE Structure calculated theoretically
TWI Structure determined on a twinned
crystalXDP X-ray diffraction (powder)
In addition to the standard remarks there may
also be additional comments (e. g. cells of isomorphic compounds if given in the paper).

REFERENCES

Standard remarks and the related full text that
may be completed by additional information if
available:

References in ICSD only quote the initial publication. References in ICSD contain the following
information:

ABC Absolute configuration given
AHT Anharmonic temperature factors given
COA Published data has been corrected
through correspondence with theauthorCOR This publication corrects errors in an
earlier one
DIS Disordered structure that cannot
adequately be described by numericalparameters
EDP Electron diffraction (powder)
EDS Electron diffraction (single crystal)
EMP Electron microscopy of a single powder
particle
ESC Electronic structure calculations
MAG Magnetic structure also determined
MIN Compound with mineral name
MOD Modulated structure or misfit-layer
structure
NDP Neutron diffraction (powder)
NDS Neutron diffraction (single crystal)
NMR NMR spectroscopy data given
ODS Order-disorder structure
PDF The structure has been assigned a PDF
numberPOL Polytype structure
PRE Pressure in MPa
RVP Rietveld profile refinement applied
SFP Structure determined from projections
SNP Synchrotron radiation (powder)
SNS Synchrotron radiation (single crystal)• Title of the publication
The title of the publication is given in English,
French or German.
• Citation
The citation includes the year, the CODEN(with check-letter) for journals, volume, firstpage and last page.
• Authors
The surname is given followed by the
initials of the first name. Some authors
may be written differently depending on
the language of the publication, e. g.,
Gladyshevskii (in Russian) or Hladyshevsky(in Ukrainian). In a few cases in Chinese
author names first or last name may beinterchanged. Please inform us about any
wrong writings.
• DOI
The Digital Object Identifier for the article isretrieved through CrossRef or supplied by the
publisher and inserted in the reference of
ICSD as a link to assure direct access to thefull text• Article ID
Several online-only journals publish articles
that have article numbers. In those cases
an article ID number will usually replace thefamiliar pagination because this numberingsystem simplifies the publication process. In
cases where we can define a page number,
we will include it in addition to the Article ID.

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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MINERALS
The names of minerals are included according
to the publication. The names acknowledged by
the IMA are listed in an additional field if they areavailable.
We distinguish between natural and synthetic minerals. In the case of natural minerals, theplace of discovery is also mentioned.

The chemical name for organometallic compounds is very complex. In the case of organometallic compounds, only parts are also used as thechemical name.
In most cases, the chemical name is taken fromthe corresponding publication. The chemicalname does not always correspond to the IUPAC
standards.

HERMANN–MAUGUIN SPACE GROUPSYMBOL
EXAMPLES
CC10404
Mineral name: Dolomite
Mineral origin: Binnenthal, Switzerland
CC16916
Mineral name: Anglesite
Mineral origin: Monte Poni, Sardinia, Italy
CC24946
Mineral name: Grossular
Mineral origin: Asbesto, Quebec, Canada

CHEMICAL NAMESThis field contains the chemical name in English
with oxidation state where necessary and corresponding to the first formula. This formula iscalculated from all atoms with defined atomic coordinates. If undetermined atoms are included aremark is displayed in the atomic coordinates list.
Oxidation state is given in Roman numbers.
Phase information may be given after the hyphen. If
two structures seem to be identical and have slightdifferences only due to special conditions details
are given after a hyphen (e. g. doped material).

EXAMPLES
CC10404 Calcium magnesium dicarbonate
CC16916 Lead sulfate(VI)CC24946 Tricalcium dialuminium silicate

18This symbol is used according to the International
Tables for X-Ray Crystallography. If different origin
choices are available, those space groups withorigin at center are characterized by an additional “z”, while an additional “s” is being used forspecial origins. Rhombohedral space groups withhexagonal cells are marked with an additional “h”(“hr” for reverse setting). Full symbols are used
for monoclinic space groups to show the choiceof the unique axis.
For all space groups a list of coordinate tripletsof a general position is given. Space groups thatare not included in the International Tables needa critical evaluation. In a numerical database, aspace group “F132/m” may cause some trouble
in statistical searches. It should be replaced by
R3mH (with 3/4 volume).
EXAMPLE
CC10404
CC16916
CC24916

R3H
Pnma
Ia3d

ANX FORMULA
The ANX formula is generated according to the following rules:• H+ is not taken into account, even if
coordinates are available.
• The coordinates for all sites of all other atoms
must be determined.
• Different atom types on the same position(e. g. for solid solutions) are being treated as

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

one single atom type. The relevant atom type
is the one with the highest site occupation
factor. If the SOFs are equal the first atom
type is the relevant atom type.
• Exception to this rule: if anions and cations
occupy the same site they will not be treatedas one atom type.
• All sites occupied by the same atom typeare combined unless the oxidation state isdifferent.
Fe2+(Fe3+)2O4 → AB2X4(Fe2.6667+)3O4 → A3X4
• For each atom type the multiplicities are
multiplied by the SOFs and the products areadded. The sums are rounded and divided by
the greatest common divisor.
• If the rounded sum is equal to zero all sums
are multiplied by a common factor so that thesmallest sum is equal to 1.0, so no element
will be omitted.
• Cations are assigned the symbols A–M,
neutral atoms N–R and anions are assigned
X, Y, Z, S–W.
• The symbols are sorted alphabetically andthe characters are assigned according toascending indices: AB2X4, not A2BX4.
All ANX formulae with more than 4 cation symbols, 3 neutral symbols or 3 anion symbols aredeleted. This measure limits the number of different ANX formulae.

EXAMPLE
Structural formula
CC10404
CaMg(CO3)2
CC16916
Pb(SO4)CC24946
Ca3Al2(SiO4)3

ANX formula
ABC2X6
ABX4
A2B3C3X12

PEARSON SYMBOLS
Three datasets are required to create a Pearson
symbol:1. Symbol for the crystal system• a = triclinic (anorthic)• m = monoclinic• o = orthorhombic• c = cubic• h = trigonal• h = hexagonal• t = tetragonal

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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2. Symbol for Bravais-Type• P = primitive• F = face centered• I = body centered• R = rhombohedral• S = side centered
In ICSD the older A, B, C notation for Pearson symbols has been substituted by “S” symbol (oneside centered) for monoclinic and orthorhombic
space groups (for monoclinic also I). This way thePearson Symbol has become independent of thecell transformations.
3. The number of atoms in the unit cellThis number is calculated from the sum of all
multiplicities and the respective site occupation
factors for each atom type. The data are rounded.
The number of atoms for rhombohedral spacegroups depends on the trigonal or hexagonalsetting of the space group. In ICSD the numberof atoms in hexagonal settings of rhombohedral
space groups should be divided by 3 to match thedata from Pearson’s Handbook and to get numbers invariant to cell transformations.

WYCKOFF SEQUENCE
Sites with SOF < 1 are treated in analogy to thetreatment for the ANX formula (see above). Symmetrically equivalent sites (represented by a Wyckoff letter) are counted, and the number is given
along with the Wyckoff letter.
The Wyckoff letters are sorted alphabetically (descending sort) and written along with their number, each new Wyckoff letter is separated by ablank.
EXAMPLE
CC10404
CC16916
CC24946

This sequence is not unique, but depends insome space groups on the choice of origin. E.g.,
for spinels the sequence changes from “f d a” to“f c b” after an origin shift of ½ ½ ½.

EXAMPLE
CC10404
CC16916
CC24946

20

fcba
d c4
hdca

hR10
oP24
cl160

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASESTRUCTURE TYPES
Structure types were introduced into ICSD in 2007
as an approach to describe structural similarity
between inorganic structures. This is still an ongoing process, i.e. quality enhancements resp.
introducing new types is continuously in progressin the background. ICSD structure types may best
be classified as “isoconfigurational”, according
to the definition by IUCr [1]. In this definition, isoconfigurational structures must conform to certain structural parameters (descriptors) like:••••Space group
Pearson symbol
Wyckhoff sequence
ANX formula

In the ICSDWeb interface just the most basic descriptors (the listed ones above) are available forsearching in the ICSD database, whereas the assignment of type information indeed is realized ina batch procedure step for each new ICSD update.
This data mining process makes use of more thanthe previously listed descriptors. The total list ofdescriptors is shown in the Excel file, see information box).
In this listing there appear further important descriptors as c/a-ratio, monclinic angles, chemiEXAMPLE

Of these descriptors the Wyckhoff sequence is
crucial, because it describes the atomic arrangement in the unit cell. Each structure type is defined by a set of some or all or even more than of
the listed descriptors, as has been explained indetail in [2].

CC10404
CC16916
CC24946

Dolomite#CaMg(CO3)2
Barite#BaSO4
Garnet#Ca3Al2Ca3Al2(SiO4)3

cal restraints (forbidden and essential elements
needed for correct labelling of entries with type
information).

LITERATURE[1]

Lima-de-Faria, F., Hellner, E., Liebau, F., Makovicky, E. & Parthé, E., Acta Cryst. (1990).
A46, 1-11, “Nomenclature of inorganic structure types. Report of the International
Union of Crystal­lography Commission on the crystallographic Nomenclature Subcommitte on the Nomen­clature of Inorganic Structure Types”, https://doi.org/10.1107/
S0108767389008834[2] Allmann, R. & Hinek, R., Acta Cryst. A63 (2007), 412–417, “The introduction of structure
types into the Inorganic Crystal Structure Database ICSD“, http://dx.doi.org/10.1107/
S0108767307038081[3] Excel list containing all structure type descriptors is available in ICSD on the Structure
Type search mask

FIZ Karlsruhe · SCIENTIFIC MANUAL ICSD DATABASE

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EXISTING PUBLICATIONS
Original publication to be cited in scientific work referring to the ICSD database:
Bergerhoff, G. & Brown, I.D. in “Crystallographic Databases”, F.H. Allen et al. (Hrsg.) Chester, International Union of Crystallography, (1987).
Zagorac, D., Müller, H., Ruehl, S., Zagorac, J. & Rehme, S., J. Appl. Cryst. 52 (2019), 918-925, “Recent
developments in the Inorganic Crystal Structure Database: theoretical crystal structure data and related features”, https://doi.org/10.1107/S160057671900997X.
Behrens, H., Luksch, P., Acta Cryst. B62 (2006), 993–1001, “A bibliometric study in crystallography”,
https://doi.org/10.1107/S0108768106030278.
Belsky, A., Hellenbrandt, M., Karen, V. L. & Luksch, P., Acta Cryst. B58 (2002), 364–369, “New developments in the Inorganic Crystal Structure Database (ICSD): accessibility in support of materials researchand design”. http://dx.doi.org/10.1107/S0108768102006948.
Further publications see: https://icsd.products.fiz-karlsruhe.de/en/about/about-icsd#publications

LINKS

Link to homepage
https://icsd.products.fiz-karlsruhe.de/Access to the database
https://icsd.fiz-karlsruhe.de22

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not so much to obtain new facts as todiscover new ways of thinking about
them«
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icsd@fiz-karlsruhe.de© FIZ Karlsruhe · September 2021 · Cover photo and photos on pages 2, 3, 9, 11, 16, 19, 20, 22 and 23: Wendelin Detemple