A consistent approximation scheme beyond RPA for bosons
نویسنده
چکیده
In this paper, we develop a consistent extension of RPA for bosonic systems. In order to illustrate the method, we consider the case of the anharmonic oscillator. We compare our results with those obtained in mean-field and standard RPA approaches, with the exact ones and show that they are very close to the exact ones.
منابع مشابه
Beyond the random-phase approximation for the electron correlation energy: the importance of single excitations.
The random-phase approximation (RPA) for the electron correlation energy, combined with the exact-exchange (EX) energy, represents the state-of-the-art exchange-correlation functional within density-functional theory. However, the standard RPA practice--evaluating both the EX and the RPA correlation energies using Kohn-Sham (KS) orbitals from local or semilocal exchange-correlation functionals-...
متن کاملA ug 2 00 5 Spectral properties of nuclear matter
We review self-consistent spectral methods for nuclear matter calculations. The in-medium T −matrix approach is conserving and thermodynamically consistent. It gives both the global and the single-particle properties the system. The T −matrix approximation allows to address the pairing phenomenon in cold nuclear matter. A generalization of nuclear matter calculations to the superfluid phase is ...
متن کاملDensity instabilities in a two-dimensional dipolar Fermi gas.
We study the density instabilities of a two-dimensional gas of dipolar fermions with aligned dipole moments. The random phase approximation (RPA) for the density-density response function is never accurate for the dipolar gas, and so we incorporate correlations beyond RPA via an improved version of the Singwi-Tosi-Land-Sjölander scheme. In addition to density-wave instabilities, our formalism c...
متن کاملDescribing static correlation in bond dissociation by Kohn-Sham density functional theory.
We show that density functional theory within the RPA (random phase approximation for the exchange-correlation energy) provides a correct description of bond dissociation in H(2) in a spin-restricted Kohn-Sham formalism, i.e., without artificial symmetry breaking. We present accurate adiabatic connection curves both at equilibrium and beyond the Coulson-Fisher point. The strong curvature at lar...
متن کاملRefining the American Joint Committee on Cancer Staging Scheme For Resectable Pancreatic Ductal Adenocarcinoma Using Recursive Partitioning Analysis
Purpose: It remains unclear whether the recently proposed 8th edition of the American Joint Committee on Cancer (AJCC) staging scheme for pancreatic ductal adenocarcinoma (PDAC) outperforms the 7th edition. We assessed the prognostic performance of both these schemes and performed recursive partitioning analysis (RPA) to objectively regroup the 7th and 8th AJCC stages and derive a refined stagi...
متن کامل