ConstantID

Atomic, natural and X-ray units

Atomic units, natural units, the electron volt, the dalton and X-ray length units, with their SI values.

Units exact eV Electron volt 1.602 176 634 × 10−19 J

All 42 values

SymbolQuantityValue (uncertainty)UnitRel. unc.
Å* Angstrom star 1.000 014 95(90) × 10−10 m 9.0 × 10−7
e3a03/Eh2 Atomic unit of 1st hyperpolarizability 3.206 361 2996(15) × 10−53 C3 m3 J−2 4.7 × 10−10
e4a04/Eh3 Atomic unit of 2nd hyperpolarizability 6.235 379 9735(39) × 10−65 C4 m4 J−3 6.3 × 10−10
ℏ Atomic unit of action 1.054 571 817… × 10−34 J s exact
e Atomic unit of charge 1.602 176 634 × 10−19 C exact
e/a03 Atomic unit of charge density 1.081 202 386 77(51) × 1012 C m−3 4.7 × 10−10
eEh/ℏ Atomic unit of current 6.623 618 237 5082(72) × 10−3 A 1.1 × 10−12
ea0 Atomic unit of electric dipole moment 8.478 353 6198(13) × 10−30 C m 1.5 × 10−10
Eh/ea0 Atomic unit of electric field 5.142 206 751 12(80) × 1011 V m−1 1.6 × 10−10
Eh/ea02 Atomic unit of electric field gradient 9.717 362 4424(30) × 1021 V m−2 3.1 × 10−10
e2a02/Eh Atomic unit of electric polarizability 1.648 777 272 12(51) × 10−41 C2 m2 J−1 3.1 × 10−10
Eh/e Atomic unit of electric potential 27.211 386 245 981(30) V 1.1 × 10−12
ea02 Atomic unit of electric quadrupole moment 4.486 551 5185(14) × 10−40 C m2 3.1 × 10−10
Eh Atomic unit of energy 4.359 744 722 2060(48) × 10−18 J 1.1 × 10−12
Eh/a0 Atomic unit of force 8.238 723 5038(13) × 10−8 N 1.6 × 10−10
a0 Atomic unit of length 5.291 772 105 44(82) × 10−11 m 1.5 × 10−10
ℏe/me Atomic unit of magnetic dipole moment 1.854 802 013 15(58) × 10−23 J T−1 3.1 × 10−10
ℏ/ea02 Atomic unit of magnetic flux density 2.350 517 570 77(73) × 105 T 3.1 × 10−10
e2a02/me Atomic unit of magnetizability 7.891 036 5794(49) × 10−29 J T−2 6.2 × 10−10
me Atomic unit of mass 9.109 383 7139(28) × 10−31 kg 3.1 × 10−10
ℏ/a0 Atomic unit of momentum 1.992 851 915 45(31) × 10−24 kg m s−1 1.6 × 10−10
e2/a0Eh Atomic unit of permittivity 1.112 650 056 20(17) × 10−10 F m−1 1.5 × 10−10
ℏ/Eh Atomic unit of time 2.418 884 326 5864(26) × 10−17 s 1.1 × 10−12
a0Eh/ℏ Atomic unit of velocity 2.187 691 262 16(34) × 106 m s−1 1.6 × 10−10
xu(Cu Kα1) Copper x unit 1.002 076 97(28) × 10−13 m 2.8 × 10−7
eV Electron volt 1.602 176 634 × 10−19 J exact
a Lattice parameter of silicon 5.431 020 511(89) × 10−10 m 1.6 × 10−8
d220 Lattice spacing of ideal Si (220) 1.920 155 716(32) × 10−10 m 1.7 × 10−8
Vm(Si) Molar volume of silicon 1.205 883 199(60) × 10−5 m3 mol−1 5.0 × 10−8
xu(Mo Kα1) Molybdenum x unit 1.002 099 52(53) × 10−13 m 5.3 × 10−7
ℏ Natural unit of action 1.054 571 817… × 10−34 J s exact
ℏ Natural unit of action in eV s 6.582 119 569… × 10−16 eV s exact
mec2 Natural unit of energy 8.187 105 7880(26) × 10−14 J 3.2 × 10−10
mec2 Natural unit of energy in MeV 0.510 998 950 69(16) MeV 3.1 × 10−10
λ¯C Natural unit of length 3.861 592 6744(12) × 10−13 m 3.1 × 10−10
me Natural unit of mass 9.109 383 7139(28) × 10−31 kg 3.1 × 10−10
mec Natural unit of momentum 2.730 924 534 46(85) × 10−22 kg m s−1 3.1 × 10−10
mec Natural unit of momentum in MeV/c 0.510 998 950 69(16) MeV/c 3.1 × 10−10
ℏ/mec2 Natural unit of time 1.288 088 666 44(40) × 10−21 s 3.1 × 10−10
c Natural unit of velocity 299 792 458 m s−1 exact
ℏc Reduced Planck constant times c in MeV fm 197.326 9804… MeV fm exact
u Unified atomic mass unit 1.660 539 068 92(52) × 10−27 kg 3.1 × 10−10