function angstroms2eV(angstroms) result(EeV)
real(double), intent(in) :: angstroms
real(double) :: EeV
end function angstroms2eV
function eV2angstroms(EeV) result(angstroms)
real(double), intent(in) :: EeV
real(double) :: angstroms
end function eV2angstroms