Physical Constants
Last Update:
12/31/2000
Here are summarized various conversion factors and physical constants used by Gaussian 98 in converting from standard to atomic units. All quantities used in calculations inside Gaussian 98 are in atomic units; the conversion factors are used only when processing input or generating printed output.
RAW CONSTANTS
The constants which are stored directly in the program are:
1 Bohr (a0) = 0.529177249 Å [281]
1 Atomic mass unit (amu) = 1.6605402 x 10**-27 kilograms [281]
1 Electron charge (e) = 4.803242 x 10**-10 ESU [287] = 1.602188 x 10**-19 Coulombs [288]
Planck's constant (h) = 6.6260755 x 10**-34 Joule-secs [281]
Avogadro's number (NA) = 6.0221367 x 10**23 [281]
1 Calorie = 4.184 Joules [289]
1 Hartree = 4.3597482 x 10**-18 Joules [281]
Speed of light (c) = 2.99792458 x 10**10 cm/sec [289]
Boltzman constant (k) = 1.380658 x 10**-23 Joules/degree [281]
Inverse fine structure constant (
-1) = 137.0359895 [281]
Molar volume of ideal gas at 273.15 K = 0.022411 m**3 [281]
CONVERSION FACTORS
The following useful conversion factors can be derived from the above:
Electron mass = 0.910953 x 10**-30 kg
Proton mass = 1836.1527 electron mass
1 Atomic mass unit = 1822.8880 electron mass
1 Electron volt (eV) = 23.06035 kcal/mol
1 Hartree = 627.5095 kcal/mol = 27.2116 eV
1 Bohr-electron = 2.541765 Debye
1 Debye**2-angstrom**-2-amu**-1 = 42.2547 km-mol**-1 = 5.82587 x 10**-3 cm**-2-atm**-1 at STP
1 Hartree**(-1/2)-Bohr**-1-amu**(-1/2) = 219474.7 cm**-1