Conversions & Constants


Various useful conversion factors (physical chemistry/chemical physics)
  • 1 K  = 0.69503565 cm-1
  • 1 cm-1 = 1.88365157*10-4 fs-1
  • 1 K = 1.3092050*10-4 fs-1
  • 1 eV  = 8065.544 cm-1
  • 1 eV = 1.519267 fs-1=1/(0.6582120 fs); (conversion is done evaluating energy as hbar/t)
  • 1 eV = 1241.25 nm (as wavelength)
  • 1 eV = 11605 K (energy in temperature units)
  • 1 a.m.u. = 1822.89 a.u.  (atomic mass unit in atomic units, i.e., in electron mass)


CODATA Internationally recommended values of the Fundamental Physical Constants



Fortran 90 module for atomic units (aunits.f90)

!
!********************************************************************
!
!  Atomic units module
!  Updated 04/18/2012
!
!********************************************************************
!
   module aunits
   implicit none
   save

   ! Energy
   real(8),parameter::Eatom_eV=27.2113845d0 ! Hartree in eV
   real(8),parameter::Eatom_meV=27.2113845d3 ! Hartree in meV
   real(8),parameter::Eatom_K=3.1577464d5 ! Hartree in K
   real(8),parameter::Eatom_pJ=4.3597482d-6 ! Hartree in pJ (pico Joule)

   ! Distance
   real(8),parameter::Datom_nm=5.291772d-2 ! Bohr radius in nm
   real(8),parameter::Latom_A=5.291772d-1 ! Bohr radius in Angstroms

   ! Time
   real(8),parameter::Tatom_ps=2.418884326505d-5 ! Atomic time in ps
   real(8),parameter::Tatom_fs=2.418884326505d-2 ! Atomic time in fs

   ! Velocity
   real(8),parameter::Vatom_c=7.2973525698d-3 ! fine structure constant  

   ! Mass
   real(8),parameter::Matom_g=9.1093826d-28 ! Electron mass in grams
   real(8),parameter::Matom_amu=5.48579938d-4 ! Electron mass in a.m.u.

   end module aunits
!

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