Isotope shift in a beryllium atom

We calculate the isotope shift of $2{}^1{P}_0-2{}^1{S}_0$, $3{}^1{S}_0-2{}^1{S}_0$ transitions and of the $2{}^1{S}_0$ ionization potential in the four-electron beryllium atom. The achieved precision is high enough to make possible the accurate determination of the nuclear charge radii from the experimental isotope shifts. This calls for corresponding measurements and opens the window for the determination of charge radii of heavier nuclei.