Benchmark calculations of low-lying triplet states of Be atom

Benchmark variational calculations of several lowest triplet states of the beryllium atom are reported. The wave functions of the states were expanded in terms of highly optimized explicitly correlated Gaussian basis sets and accurate energies are deterimed assuming finite nuclear mass of the atom. These wave functions were used to compute various expectation values, including those that appear in the leading relativistic and QED corrections. Density distributions and pair correlation functions are analyzed for both electrons an nucleus.