Hornyak, IstvanAdamowicz, LudwikBubin, Sergiy2019-12-182019-12-182019-09-04Hornyák, I., Adamowicz, L., & Bubin, S. (2019). Ground and excited S 1 states of the beryllium atom. Physical Review A, 100(3), 032504.http://nur.nu.edu.kz/handle/123456789/4472Benchmark calculations of the total and transition energies of the four lowest S-1 states of the beryllium atom are performed. The computational approach is based on variational calculations with finite mass of the nucleus. All-particle explicitly correlated Gaussian (ECG) functions are used to expand the total non-Born-Oppenheimer nonrelativistic wave functions and the ECG exponential parameters are optimized using the standard variational method. The leading relativistic and quantum electrodynamics energy corrections are calculated using the first-order perturbation theory. A comparison of the experimental transition frequencies with the ones calculated in this work shows excellent agreement. The deviations of 0.02-0.09 cm(-1) are well within the estimated error limits for the experimental values.enAttribution-NonCommercial-ShareAlike 3.0 United StatesArticle