Units Of Measure

    Geometries
    Cartesian coordinates are typically given in Ångstroms (Å), but are also available in nanometers (nm) and atomic units (au).

    Bond distances are typically given in Å, but are also available in nm and au. Bond angles and dihedral angles are given in degrees (°).

    Surface areas are typically given in Å 2 and volumes inÅ3, but are also available in nm2 (nm3) and au2 (au3).

    1 Å = 0.1 nm = 1.889762 au


    Energies, Heats of Formation and Strain Energies
    Total energies from Hartree-Fock, density functional and MP2 calculations are typically given in au, but are also available in kcal/mol, kJ/mol and electron volts (eV).

    Heats of formation from semi-empirical calculations are typically given in kcal/mol, but are also available in au, kJ/mol and eV.

    Strain energies from molecular mechanics calculations are typically given in kcal/mol, but are also available in au, kJ/mol and eV.


    Orbital Energies
    Orbital energies from Hartree-Fock, density functional and MP2 calculations are typically given in au, but are also available in kcal/mol, kJ/mol and eV.

    Orbital energies from semi-empirical calculations are typically given in eV, but are also available in kcal/mol, kJ/mol and au.


    Energy Conversionsa
      au kcal/mol kJ/mol eV
    1 au - 6.275 (2) 2.625 (3) 2.721 (1)
    1 kcal/mol 1.593 (-3) - 4.184 4.337 (-2)
    1 kJ/mol 3.809 (-4) 2.390 (-1) - 1.084 (-2)
    1 eV 3.675 (-2) 2.306 (1) 9.224 (1) -
    a)exponent follows in parenthesis, e.g. 1.593(-3) = 1.593 x 10-3


    Electron Densities, Spin Densities, Dipole Moments, Charges and Electrostatic Potentials
    Electron densities and spin densities are given in electrons/au3.

    Dipole moments are given in debyes.

    Atomic charges are given in electrons.

    Electrostatic potentials are given in kcal/mol.


    Vibrational Frequencies
    Vibrational frequencies are given in wavenumbers (cm-1).


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