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:

α Α \a \A alpha
β Β \b \B beta
χ Χ \c \C chi
δ Δ \d \D delta
ε Ε \e \E epsilon
φ Φ \f \F phi
γ Γ \g \G gamma
η Η \h \H eta
ι Ι \i \I iota
κ Κ \k \K kappa
λ Λ \l \L lambda
μ Μ \m \M mu
ν Ν \n \N nu
ο Ο \o \O omicron
π Π \p \P pi
θ Θ \q \Q theta
ρ Ρ \r \R rho
σ Σ \s \S sigma
τ Τ \t \T tau
υ Υ \u \U upsilon
ω Ω \w \W omega
ξ Ξ \x \X xi
ψ Ψ \y \Y psi
ζ Ζ \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):

\' acute (é) \" umlaut (ü) \= overbar
\` grave (à) \~ tilde (ñ) \. overdot
\^ circumflex (â) \; ogonek \< hacek
\, cedilla (ç) \> Hungarian umlaut \( breve

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 (tex2html_wrap120) \/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:

superscripts Csp^3^ for Csp3
subscripts U~eq~ for Ueq

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 -+ tex2html_wrap_inline104
\\db double bond \\square square
\\tb triple bond \\neq tex2html_wrap_inline108
\\ddb delocalized double bond \\rangle tex2html_wrap_inline110
\\sim tex2html_wrap_inline98 \\langle tex2html_wrap_inline112
(N.B. ~  is the code for subscript) \\rightarrow tex2html_wrap_inline114
\\simeq tex2html_wrap_inline100 \\leftarrow tex2html_wrap_inline116
\\infty tex2html_wrap_inline102    

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

Acta Crystallographica Section E: Crystallographic Communications is an open-access journal. For more information, please visit

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