pyscivr.units module

Physical constants and unit conversion factors in the internal unit system.

The internal unit system is Angstrom [length], eV [energy], atomic mass unit (amu) [mass], elementary charge [charge], Kelvin [temperature] and mol [amount of substance]. The time unit is derived as Angs * sqrt(amu / eV) (about 10.18 fs).

Each name below is the value of the unit or constant in the internal unit system, so multiplying converts into the internal units and dividing converts out of them:

from pyscivr.units import Hartree, FemtoSec

ener = -1.17 * Hartree  # Hartree -> eV
t_fs = t / FemtoSec     # internal time -> fs

Available names:

• Length: Metre, nm, cm, Angs, Bohr.

• Energy: Joule, eV, Hartree, Ry, CmInv, Hz, kcal.

• Mass: kg, gram, amu, me.

• Charge: C, e.

• Temperature and amount of substance: Kelvin, mol.

• Time: Sec, NanoSec, PicoSec, FemtoSec.

• Constants: HBar, HPlanck, KB, SpeedOfLight, NAvo, Mu0, Eps0, E (elementary charge), MPro, MNeu, MEle, Debye.

Each constant is also available in SI units with the suffix _SI (e.g. HBar_SI).