Units of Measure

Atomic Units

• \(\mathrm B\) – Bohr radius, atomic unit of length, equal to \(0.52917721067\ \mathring{\mathrm A}\) or \(0.52917721067\times 10^{-10}\ \mathrm m~~\) [NISTCUU_B]
• \(\mathrm{D_a}\) – Atomic unit of electric dipole moment, equal to \(\mathrm{q\, B} = 8.478353552\times 10^{-30}~\mathrm{C\!\cdot\! m}~~\) [NISTCUU_Da] and approximately \(2.542~\mathrm D~~\) [Row08]
• \(\mathrm{E_h}\) – Hartree, atomic unit of energy, equal to \(4.35974465\times 10^{-18}~\mathrm J~~\) [NISTCUU_Eh]
• \(\mathrm{m_e}\) – Electron mass, atomic unit of mass, equal to \(9.10938356\times 10^{-31} ~\mathrm{kg}~~\) [NISTCUU_me]
• \(\mathrm{q}\) – Electron charge, atomic unit of charge, equal to \(1.6021766208\times 10^{-19}~\mathrm{C}~~\) [NISTCUU_q]
• \(\mathrm{T_a}\) – Atomic time unit, equal to \(2.4188843265\times 10^{-17}\ \mathrm s~~\) [NISTCUU_Ta]

Other Units

• \(\mathrm{cyc}\) – Numerical value of \(2\pi\ \left(\frac{\mathrm{cyc}}{2\pi}=1\right)\), serving to convert angular frequencies into cyclic frequencies
• \(\mathrm{u}\) – unified atomic mass unit; equal to \(1822.8885\ \mathrm{m_e}~\) [NISTCUU_me_u] or \(1.660539040\times 10^{-27}\ \mathrm{kg}~~\) [NISTCUU_u_kg]