Estimating compressibility from maximal-mass compact star observations

We investigated recent observation data of pulsar masses of PSR J0740+6620, PSR J0348+0432, and PSR J1614−2230 based on the extended σ-ω model. We assumed that these pulsars are maximal mass compact star, which suggest that the core approximation can be applied. Using the linear relations between the microscopic and macroscopic parameters of neutron stars suggested by this model, we estimated the values of the nucleon Landau mass and nuclear compressibility mL=776.0−84.9+38.5 MeV and K=242.7−28.0+57.2 MeV, respectively.

Frozen Core Approximation and Nuclear Screening Effects in Single Electron Capture Collisions

Differential cross sections (DCS) for single electron capture from helium by heavy ion impact are calculated using a frozen core 3-body model and an active electron 4-body model within the first Born approximation. DCS are presented for H+, He2+, Li3+, and C6+ projectiles with velocities of 1 MeV/amu and 10 MeV/amu. In general, the DCS from the two models are found to differ by about one to two orders of magnitude with the active electron 4-body model showing better agreement with experiment. Comparison of the models reveals two possible sources of the magnitude difference: the inactive electron’s change of state and the projectile–target Coulomb interaction used in the different models. Detailed analysis indicates that the uncaptured electron’s change of state can safely be neglected in the frozen core approximation, but that care must be used in modeling the projectile–target interaction.

A New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

We present a fully analytical implementation of the core-valence separation (CVS) scheme for the equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method for calculations of core-level states. In the spirit of the original CVS approximation proposed by Cederbaum, Domcke and Schirmer, pure valence excitations are excluded from the EOM target space and the frozen-core approximation is imposed on the reference-state amplitudes and multipliers. This yields an efficient, robust, and accurate EOM-CCSD framework for calculations of excitation and ionization energies as well as state and transition properties (e.g., spectral intensities, natural transition and Dyson orbitals). The accuracy of the new scheme is improved relative to the results obtained applying the CVS only during the solution of the EOM eigenvalue equations. The errors in absolute excitation/ionization energies relative to the experimental reference data are of the order of 0.2{3.0 eV, depending on the K-edge considered and on the basis set used, and the shifts are systematic for each edge.<br>

A New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

We present a fully analytical implementation of the core-valence separation (CVS) scheme for the equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method for calculations of core-level states. In the spirit of the original CVS approximation proposed by Cederbaum, Domcke and Schirmer, pure valence excitations are excluded from the EOM target space and the frozen-core approximation is imposed on the reference-state amplitudes and multipliers. This yields an efficient, robust, and accurate EOM-CCSD framework for calculations of excitation and ionization energies as well as state and transition properties (e.g., spectral intensities, natural transition and Dyson orbitals). The accuracy of the new scheme is improved relative to the results obtained applying the CVS only during the solution of the EOM eigenvalue equations. The errors in absolute excitation/ionization energies relative to the experimental reference data are of the order of 0.2{3.0 eV, depending on the K-edge considered and on the basis set used, and the shifts are systematic for each edge.<br>

A New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

We present a fully analytical implementation of the core-valence separation (CVS) scheme for the equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method for calculations of core-level states. In the spirit of the original CVS approximation proposed by Cederbaum, Domcke and Schirmer, pure valence excitations are excluded from the EOM target space and the frozen-core approximation is imposed on the reference-state amplitudes and multipliers. This yields an efficient, robust, and accurate EOM-CCSD framework for calculations of excitation and ionization energies as well as state and transition properties (e.g., spectral intensities, natural transition and Dyson orbitals). The accuracy of the new scheme is improved relative to the results obtained applying the CVS only during the solution of the EOM eigenvalue equations. The errors in absolute excitation/ionization energies relative to the experimental reference data are of the order of 0.2{3.0 eV, depending on the K-edge considered and on the basis set used, and the shifts are systematic for each edge.<br>

A New and Efficient Equation-of-Motion Coupled-Cluster Framework for Core-Excited and Core-Ionized States

We present a fully analytical implementation of the core-valence separation (CVS) scheme for the equation-of-motion (EOM) coupled-cluster singles and doubles (CCSD) method for calculations of core-level states. In the spirit of the original CVS approximation proposed by Cederbaum, Domcke and Schirmer, pure valence excitations are excluded from the EOM target space and the frozen-core approximation is imposed on the reference-state amplitudes and multipliers. This yields an efficient, robust, and accurate EOM-CCSD framework for calculations of excitation and ionization energies as well as state and transition properties (e.g., spectral intensities, natural transition and Dyson orbitals). The accuracy of the new scheme is improved relative to the results obtained applying the CVS only during the solution of the EOM eigenvalue equations. The errors in absolute excitation/ionization energies relative to the experimental reference data are of the order of 0.2{3.0 eV, depending on the K-edge considered and on the basis set used, and the shifts are systematic for each edge.<br>