Publications by Stefano Falletta

Nonempirical semilocal density functionals for correcting the self-interaction of polaronic states

Through the use of the piecewise-linearity condition of the total energy, we correct the self-interaction for the study of polarons by constructing nonempirical functionals at the semilocal level of theory. We consider two functionals, the gamma DFT and mu ...

Aip Publishing2024

Migration of hole polarons in anatase and rutile TiO2 through piecewise-linear functionals

Alfredo Pasquarello, Stefano Falletta, Giorgio Palermo

We investigate the migration properties of hole polarons in rutile and anatase TiO2 using Hubbard U semilocal and hybrid functionals with parameters set to enforce the piecewise linearity condition. The polarons in anatase and in rutile are found to be sta ...

2024

Range-separated hybrid functionals for accurate prediction of band gaps of extended systems

Alfredo Pasquarello, Stefano Falletta, Jing Yang

In this work, we systematically evaluate the accuracy in band gap prediction of range-separated hybrid functionals on a large set of semiconducting and insulating materials and carry out comparisons with the performance of their global counterparts. We obs ...

NATURE PORTFOLIO2023

Self-Interaction and Polarons in Density Functional Theory

Stefano Falletta

The electron self-interaction is a long-standing problem in density functional theory and is particularly critical in the description of polarons. Polarons are quasiparticles involving charge localization coupled with self-induced lattice distortions. Sinc ...

EPFL2023

Polaron hopping through piecewise-linear functionals

Alfredo Pasquarello, Stefano Falletta

We use piecewise-linear functionals to study the polaron energy landscape and hopping rates in beta-Ga2O3, which we adopt as an example of an anisotropic material hosting multiple polaronic states. We illustrate various functionals for polaron localization ...

AMER PHYSICAL SOC2023

Chemical Trend of Nonradiative Recombination in Cu(In,Ga)Se2 Alloys

Stefano Falletta

Nonradiative recombination in Cu(In,Ga)Se2 (CIGS) solar cells has long been attributed to the antisite defects MCu (M = In, Ga), but the underlying mechanism is still elusive. Using rigorous first-principles calculations, we demonstrate that the antisites ...

American Physical Society (APS)2023

One-Shot Approach for Enforcing Piecewise Linearity on Hybrid Functionals: Application to Band Gap Predictions

Alfredo Pasquarello, Stefano Falletta, Jing Yang

We present an efficient procedure for constructing nonempirical hybrid functionals to accurately predict band gaps of extended systems. We determine mixing parameters by enforcing the generalized Koopmans’ condition on localized electron states, which are ...

2022

Hubbard U through polaronic defect states

Alfredo Pasquarello, Stefano Falletta

Since the preliminary work of Anisimov and co-workers, the Hubbard corrected DFT+U functional has been used for predicting properties of correlated materials by applying on-site effective Coulomb interactions to specific orbitals. However, the determinatio ...

NATURE PORTFOLIO2022

Polarons free from many-body self-interaction in density functional theory

Alfredo Pasquarello, Stefano Falletta

We develop a unified theoretical framework encompassing one-body and many-body forms of self-interaction. We find an analytic expression for both the one-body and the many-body self-interaction energies, and quantitatively connect the two expressions throu ...

2022

Many-Body Self-Interaction and Polarons

Alfredo Pasquarello, Stefano Falletta

We address the many-body self-interaction in relation to polarons in density functional theory. Our study provides (i) a unified theoretical framework encompassing many-body and one-body forms of self-interaction and (ii) an efficient semilocal scheme for ...

2022