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:

	A	\a	\A	alpha
	B	\b	\B	beta
	X	\c	\C	chi
		\d	\D	delta
	E	\e	\E	epsilon
		\f	\F	phi
		\g	\G	gamma
	H	\h	\H	eta
	I	\i	\I	iota
	K	\k	\K	kappa
		\l	\L	lambda
	M	\m	\M	mu
	N	\n	\N	nu
o	O	\o	\O	omicron
		\p	\P	pi
		\q	\Q	theta
	R	\r	\R	rho
		\s	\S	sigma
	T	\t	\T	tau
		\u	\U	upsilon
		\w	\W	omega
		\x	\X	xi
		\y	\Y	psi
	Z	\z	\Z	zeta

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.

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