Calculated electric quadrupole moments
The electric quadrupole moment is a measure of the charge distribution in a molecule.
The calculated quadrupole moments are reported as symmetric matrix
components in units of D Å (Debye times Angstrom) or e a02 (electron charge times bohr squared).
The currently chosen quadrupole units are D Å
See Section VII.A.8 to change units.
Please enter the chemical formula
Rules for chemical formula
- Enter a sequence of element symbols followed by numbers
to specify the amounts of desired elements (e.g., C6H6).
- Elements may be in any order.
- If only one of a given atom is desired, you may omit
the number after the element symbol.
- Parentheses may be used to group atoms.
- Multiple specifications for an atom will be added.
This means that CH3(CH2)4CH3 will be
treated the same as C6H14.
- To specify one or more of a given atom, use a
question mark (?) after the element symbol.
- To specify any number (including zero) of given
element, use an asterisk (*) after the element symbol.
- A comma delimited list of several species may be entered.
- Ions are indicated by placing + or - at the end of the formula (CH3+, BF4-, CO3--)
Species in the CCCBDB
- Mostly atoms with atomic number less than than 36 (Krypton), except for most of the transition metals.
See section I.B.1 for a periodic table view.
- Six or fewer heavy atoms and twenty or fewer total atoms.
Versions 8 and higher have a few substituted benzenes with more than six heavy atoms.
Versions 12 and higher have bromine-containing molecules.
References dealing with electric quadrupoles
Are we missing any? Please email us at