Abstracts Book - IMRC 2018

• SD1-O008 Invited Talk
MANY BODY TECHNIQUES FOR SURFACE ENERGIES, INTERLAYER
BINDING ENERGIES AND STRUCTURAL PHASE TRANSITIONS
Adrienn Ruzsinszky 1
1 Temple University, Department of Physics, United States.
The Random Phase Approximation (RPA) will soon be a standard method
beyond semilocal Density Functional Theory that naturally incorporates weak
interactions and eliminates self-interaction error in the exchange energy. RPA is
not completely perfect, however, and suffers self-correlation error as well as an
incorrect description of short-ranged correlation. To improve upon RPA, an
exchange(-correlation) kernel can be included in the calculation of the
correlation energy [1,2]. Exchange-correlation kernels can be approached in
various ways. In this work we utilize nonempirical kernels based on exact
constraints. Model kernels can introduce electronic instabilities when inverting
the response function with the kernel. To eliminate the additional cost in
comparison to RPA and avoid inversion involving the kernel, the response
function can be approximated through a low-order expansion using RPA
renormalization [3]. In this talk I will reveal the strengths and limitations of some
model kernels within the Renormalized RPA through some materials problems
such as structural phase transitions, interlayer binding energies and surface
energies [1,4,5].
Acknowledgment:
Work was supported by NSF DMR–1553022.
Keywords: many-body theory, density functional theory, materials theory
Presenting authors email: aruzsinszky@temple.edu