The search is conducted on both the Title and the Comments fields.
Strings like 'super' will return any title or comment that contains *super*.
The PDF number is often in the comments field, but it is best entered in the Remarks box.
ICSD Help : Elements (Close)
This is just a list of some of the elements in the cell. You can follow the element symbol by a number to indicate the total number of atoms of that particular
element. You may want to specify also the "Element Count", the total number of different elements.
The default logic is AND but you can also use explicitly OR and NOT.
New! Element Groups can now be used (see the Notes).
Example Elements search :(Enter the element symbols or choose from the
ICSD Help : ANX Formula, Pearson Symbol or Structure Type (Close)
An unqualified string will be assumed to be an ANX formula.
ABX6 (All ANX formulae are searched for the string "ABX6").
Otherwise, A= or P= or T= must be specified as below.
The ANX formula :
Elements with a positive oxidation state are labelled by the first letters of the alphabet (A-M),
elements with a negative oxidation state are labelled by the last letters (X-Z, W, V, U, T, S),
while elements with oxidation state 0 are labelled by the letters N-R.
The ANX formula is only calculated for fully determined structures.
Hydrogen and its isotopes, when they occur in the positive oxidation state, are disregarded.
If an element in the structure occurs in various oxidation states, this is indicated by different letters.
Within a group of letters, the letters are arranged according to increasing indices.
In the case of a defect structure, a partial site occupation is disregarded.
In mixed crystals, atoms in identical positions are labelled by the letter of the most frequent element.
If there is doubt about the oxidation state, the use of the ANX formula requires careful consideration.
(e.g. K Fe (Fe (C N)6), Ca B6, N4 S4 H4, Hg Pb P14, Cs B9 H14, ...).
The Structure Type as defined by Prof. R. Allmann (Marburg) depends on the Space Group, Pearson Symbol and Wyckoff Sequence,
all of which can otherwise be searched for seperately in ICSD. In a few cases the c/a ratio is used. Allmann Structure Types
are at present only defined for cubic and tetragonal materials.
Note that including the Structure Type in quotes eg T="AuCu3" will ensure that only "AuCu3" will be found.
ICSD Help : System (Close)
The crystal system is a rough classification of over-all crystal symmetry. Be careful in using it, since the real symmetry of many compounds is often lower than first determined.
ICSD Help : Laue Class (Close)
Be careful in using the Laue Class symmetry, since the real symmetry of many compounds is often lower than first determined.
ICSD Help : Centering (Close)
Space groups can be classed as having a center of symmetry (Centered) or Non-Centered; many non-centered cells are are also Polar.
ICSD Help : Space Group (Close)
You can select a particular space group from the Space Group Table.
Example Space Group :
P4 : Space Group starts with P and contains 4 ie any of P4, P4-, P41 etc.
"P4" : Space Group is an exact match to "P4" (quotes required).
"C2/c" : This won't work; remove the quotes and use C2/c or quote the full symbol "C12/c1".
C2/c : Space group starts with C and contains 2/c.
Cmca : Space group starts with C and contains mca with the mca setting.
Although you can give a single number, you should always specify a range of cell dimensions.
The given range should not be too small; dimensions are stored in rather large increments.
ICSD Help : Wyckoff Sequence (Close)
The Wyckoff Sequence is a (partial) list of Wyckoff positions 2a, 4b etc. You cannot search for an exact string.
When combined with the Space Group it is a powerful means of finding similar structures.
If it is used as the only criterium, searching can be long, so combine it with other criteria as below.
Example Wyckoff Sequence :
2e 2a (The symbols 2e and 2a are found in the Wyckoff sequence in any order).
The Wyckoff Symbol is a different classification based on the number of distinct a,b,c etc positions.
eg "e11" means 11 distinct e-positions. You must search on an exact substring of the Wyckoff Symbol, but to this you can add individual Wyckoff positions.
Example Wyckoff Symbol :
"e11 c" (The Wyckoff Symbol contains the exact string "e11 c").
"e11" c (The Wyckoff Symbol contains "e11" and there are atoms at Wyckoff positions c in any order).
Note: Wyckoff Symbols are listed with the structure Details, where you can search for other structures with the same symbol.
ICSD Help : Remarks (Close)
This search is conducted on both the Remarks and Tests fields.
Remarks contain information about experimental conditions.
Tests can indicate problems with the reported structure.
Example Remark or Test Codes (see the lists below) :
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s > (Ltructuoccupation1m15*(i ardeus(A)+i ardeus(X)action (powdMinimumne11"clica: 0.9*IR the SG sat Symb1"clica> (Beta aniture A contositibe foture >Note tonCoutair"2">
s > (Ltructugreats is oft0.9*(i ardeus(A)+i ardeus(X)action (powdS">".S"2">
e given b/a arelarchely bea/auci>A "Z"
The togrour thoBetai mula is onBe caran sear"2">
fulhit with ,>
ot can select"Z" in.D11"clice> as the ered unit cels.