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Browsing Physics by Subject "Benchmark variational calculations"
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Item Open Access Assessment of the accuracy the experimental energies of the 1Po 1s22s6p and 1s22s7p states of 9Be based on variational calculations with explicitly correlated Gaussians(2012) Bubin, Sergiy; Adamowicz, LudwikBenchmark variational calculations are performed for the six lowest states of the 1Po 1s22snp state series of the 9Be atom. The wave functions of the states are expanded in terms of all-particle, explicitly correlated Gaussian basis functions and the effect of the finite nuclear mass is directly included in the calculations. The exponential parameters of the Gaussians are variationally optimized using the analytical energy gradient determined with respect to those parameters. Besides providing reference non-relativistic energies for the considered states, the calculations also allow to assess the accuracy of the experimental energies of the 1Po 1s22s6p and 1s22s7p states and suggest their refinementItem Open Access Prediction of 1P Rydberg energy levels of beryllium based on calculations with explicitly correlated Gaussians(2014) Bubin, Sergiy; Adamowicz, LudwikBenchmark variational calculations are performed for the seven lowest 1s22s np (1P), n = 2. . . 8, states of the beryllium atom. The calculations explicitly include the effect of finite mass of 9Be nucleus and account perturbatively for the mass-velocity, Darwin, and spin-spin relativistic corrections. The wave functions of the states are expanded in terms of all-electron explicitly correlated Gaussian functions. Basis sets of up to 12 500 optimized Gaussians are used. The maximum discrepancy between the calculated nonrelativistic and experimental energies of 1s22s np(1P)→1s22s2 (1S) transition is about 12 cm−1. The inclusion of the relativistic corrections reduces the discrepancy to bellow 0.8 cm−1