Molecular Properties

These two papers are of general interest:
A.D.Buckingham, J.Chem.Phys. 30, 1580-1585(1959).
D.Neumann, J.W.Moskowitz J.Chem.Phys. 49, 2056-2070(1968).

All units are derived from the atomic units for distance and the monopole electric charge, as given below.
distance- 1 au = 5.291771E-09 cm
monopole- 1 au = 4.803242E-10 esu
1 esu = sqrt(g-cm**3)/sec
dipole- 1 au = 2.541766E-18 esu-cm
1 Debye = 1.0E-18 esu-cm
quadrupole - 1 au = 1.345044E-26 esu-cm**2
1 Buckingham = 1.0E-26 esu-cm**2
octupole- 1 au = 7.117668E-35 esu-cm**3
electric potential- 1 au = 9.076814E-02 esu/cm
electric field- 1 au = 1.715270E+07 esu/cm**2
1 esu/cm**2 = 1 dyne/esu
electric field gradient- 1 au = 3.241390E+15 esu/cm**3

The atomic unit for electron density is electron/bohr**3 for the total density, and 1/bohr**3 for an orbital density.

The atomic unit for spin density is excess alpha spins per unit volume, h/4*pi*bohr**3. Only the expectation value is computed, with no constants premultiplying it.

IR intensities are printed in Debye**2/amu-Angstrom**2. These can be converted into intensities as defined by Wilson, Decius, and Cross's equation 7.9.25, in km/mole, by multiplying by 42.255. If you prefer 1/atm-cm**2, use a conversion factor of 171.65 instead. A good reference for deciphering these units is A.Komornicki, R.L.Jaffe J.Chem.Phys. 1979, 71, 2150-2155. A reference showing how IR intensities change with basis improvements at the HF level is Y.Yamaguchi, M.Frisch, J.Gaw, H.F.Schaefer, J.S.Binkley, J.Chem.Phys. 1986, 84, 2262-2278.


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