CMB-lensing beyond the Born approximation

Impact of post-Born lensing on the CMB

The diagonal Born–Oppenheimer correction beyond the Hartree–Fock approximation

We report on evaluation of the diagonal Born–Oppenheimer correction ~DBOC! to the electronic energy with Hartree–Fock ~HF! and conventional correlated wave functions for general molecular systems. Convergence of both HF and configuration interaction ~CI! DBOC with the one-particle basis seems to be rather fast, with triple-z quality correlation consistent sets of Dunning et al. sufficiently com...

Wave-equation migration velocity analysis beyond the Born approximation

The Born approximation is based on the assumption of small slowness perturbation. We investigate the limits of the Born approximation when applied to wave-equation migration velocity analysis and propose two new schemes which allow for larger slowness anomalies, while improving accuracy and increasing stability. The new schemes are based on linearizations of exponential functions using bilinear...

Dispersion representations for hard exclusive processes: beyond the Born approximation

Several hard exclusive scattering processes admit a description in terms of generalized parton distributions and perturbative hard-scattering kernels. Both the physical amplitude and the hard-scattering kernels fulfill dispersion relations. We give a detailed investigation of their consistency at all orders in perturbation theory. The results shed light on the information about generalized part...

Beyond the Born-Oppenheimer approximation with quantum Monte Carlo

In this work we develop tools that enable the study of non-adiabatic effects with variational and diffusion Monte Carlo methods. We introduce a highly accurate wave function ansatz for electronion systems that can involve a combination of both fixed and quantum ions. We explicitly calculate the ground state energies of H2, LiH, H2O and FHF − using fixed-node quantum Monte Carlo with wave functi...