Greek letters and special symbols

A limited number of special characters (such as Greek letters, sub- and superscripts, and a few others) may be indicated in CIF text for typesetting purposes, using the special codes listed below.

Greek letters

In general, the corresponding letter of the Latin alphabet, prefixed by a backslash character. The complete set is:

Accented letters

Accents should be indicated by using the following codes before the letter to be modified (i.e. use \'e for an acute e):

Other characters

Other special alphabetic characters should be indicated as follows:

\%a	a-ring (å)	\?i	dotless i	\&s	German "ss" (ß)
\/o	o-slash (ø)	\/l	Polish l ()	\/d	barred d

Capital letters may also be used in these codes, so an ångström symbol (Å) may be given as \%A.

Superscripts and subscripts should be indicated by bracketing relevant characters with circumflex or tilde characters, thus:

The closing symbol is essential to return to normal text.

Other codes are also recognized by the IUCr software. These are:

\%	degree (°)	\\times	×
--	dash	+-	±
---	single bond	-+
\\db	double bond	\\square	square
\\tb	triple bond	\\neq
\\ddb	delocalized double bond	\\rangle
\\sim		\\langle
(N.B. ~  is the code for subscript)		\\rightarrow
\\simeq		\\leftarrow
\\infty

Note that \\db, \\tb and \\ddb should always be followed by a space, e.g. C=C is denoted by C\\db C.