Lucas K. Wagner
YOU?
Author Swipe
Expressivity of Determinantal Ansatzes for Neural Network Wave Functions Open
Neural network wave functions have shown promise as a way to achieve high accuracy in solving the many-body quantum problem. These wave functions most commonly use a determinant or a sum of determinants to antisymmetrize many-body orbitals…
View article: Reproducibility of fixed-node diffusion Monte Carlo across diverse community codes: The case of water–methane dimer
Reproducibility of fixed-node diffusion Monte Carlo across diverse community codes: The case of water–methane dimer Open
Fixed-node diffusion quantum Monte Carlo (FN-DMC) is a widely trusted many-body method for solving the Schrödinger equation, known for its reliable predictions of material and molecular properties. Furthermore, its excellent scalability wi…
Quantum Monte Carlo assessment of embedding for a strongly-correlated defect: interplay between mean-field and interactions Open
Point defects are of interest for many applications, from quantum sensing to modifying bulk properties of materials. Because of their localized orbitals, the electronic states are often strongly correlated, which has led to a proliferation…
View article: Enhancing high-energy powder X-ray diffraction applications using a PILATUS4 CdTe detector
Enhancing high-energy powder X-ray diffraction applications using a PILATUS4 CdTe detector Open
Hybrid photon counting detectors have significantly advanced synchrotron research. In particular, the introduction of large cadmium telluride-based detectors in 2015 enabled a whole new range of high-energy X-ray measurements. This article…
View article: Reproducibility of fixed-node diffusion Monte Carlo across diverse community codes: The case of water-methane dimer
Reproducibility of fixed-node diffusion Monte Carlo across diverse community codes: The case of water-methane dimer Open
Fixed-node diffusion quantum Monte Carlo (FN-DMC) is a widely-trusted many-body method for solving the Schrödinger equation, known for its reliable predictions of material and molecular properties. Furthermore, its excellent scalability wi…
Capturing spin fluctuations in CaCuO$_2$: $\textit{Ab initio}$ QMC calculations with multi-determinant wave functions Open
We present an advanced $\textit{ab initio}$ quantum Monte Carlo (QMC) calculation of the ground state of undoped CaCuO$_2$. We extend the traditional single-determinant Slater-Jastrow approach to include multi-determinant wave functions, i…
Ensemble variational Monte Carlo for optimization of correlated excited state wave functions Open
Variational Monte Carlo methods have recently been applied to the calculation of excited states; however, it is still an open question what objective function is most effective. A promising approach is to optimize excited states using a pe…
Particle-hole asymmetric phases in doped twisted bilayer graphene Open
Despite much theoretical work, developing a comprehensive ab initio model for twisted bilayer graphene (TBG) has proven challenging due to the inherent trade-off between accurately describing the band structure and incorporating the intera…
Ensemble variational Monte Carlo for optimization of correlated excited state wave functions Open
Variational Monte Carlo methods have recently been applied to the calculation of excited states; however, it is still an open question what objective function is most effective. A promising approach is to optimize excited states using a pe…
Downfolding from Ab Initio to Interacting Model Hamiltonians: Comprehensive Analysis and Benchmarking of the DFT+cRPA Approach Open
Model Hamiltonians are regularly derived from first-principles data to describe correlated matter. However, the standard methods for this contain a number of largely unexplored approximations. For a strongly correlated impurity model syste…
View article: Registry-dependent potential energy and lattice corrugation of twisted bilayer graphene from quantum Monte Carlo
Registry-dependent potential energy and lattice corrugation of twisted bilayer graphene from quantum Monte Carlo Open
An uncertainty in studying twisted bilayer graphene (TBG) is the minimum energy geometry, which strongly affects the electronic structure. The minimum energy geometry is determined by the potential energy surface, which is dominated by van…
View article: Implication of the double-gating mode in a hybrid photon counting detector for measurements of transient heat conduction in GaAs/AlAs superlattice structures
Implication of the double-gating mode in a hybrid photon counting detector for measurements of transient heat conduction in GaAs/AlAs superlattice structures Open
Understanding and control of thermal transport in solids at the nanoscale are crucial in engineering and enhance the properties of a new generation of optoelectronic, thermoelectric and photonic devices. In this regard, semiconductor super…
View article: <tt>PyQMC</tt>: An all-Python real-space quantum Monte Carlo module in <tt>PySCF</tt>
PyQMC: An all-Python real-space quantum Monte Carlo module in PySCF Open
We describe a new open-source Python-based package for high accuracy correlated electron calculations using quantum Monte Carlo (QMC) in real space: PyQMC. PyQMC implements modern versions of QMC algorithms in an accessible format, enablin…
View article: Implication of the double-gating mode in hybrid photon counting detector for measurements of transient heat conduction in GaAs/AlAs superlattice structures
Implication of the double-gating mode in hybrid photon counting detector for measurements of transient heat conduction in GaAs/AlAs superlattice structures Open
Understanding and control of thermal transport in solids at nanoscale is crucial to engineer and to enhance properties of a new generation of optoelectronic, thermoelectric, and photonic devices. In this regard, semiconductor superlattice …
Renormalized density matrix downfolding: A rigorous framework in learning emergent models from ab initio many-body calculations Open
We present a generalized framework, renormalized density matrix downfolding (RDMD), to derive systematically improvable, highly accurate, and nonperturbative effective models from ab initio calculations. This framework moves beyond the com…
View article: PyQMC: an all-Python real-space quantum Monte Carlo module in PySCF
PyQMC: an all-Python real-space quantum Monte Carlo module in PySCF Open
We describe a new open-source Python-based package for high accuracy correlated electron calculations using quantum Monte Carlo (QMC) in real space: PyQMC. PyQMC implements modern versions of QMC algorithms in an accessible format, enablin…
Quantification of electron correlation for approximate quantum calculations Open
State-of-the-art many-body wave function techniques rely on heuristics to achieve high accuracy at an attainable computational cost to solve the many-body Schrödinger equation. By far, the most common property used to assess accuracy has b…
Quantification of electron correlation for approximate quantum calculations Open
State-of-the-art many-body wave function techniques rely on heuristics to achieve high accuracy at an attainable cost to solve the many-body Schrödinger equation. By far the most common property used to assess accuracy has been the total e…
Revisiting the dark matter interpretation of excess rates in semiconductors Open
In light of recent results from low-threshold dark matter detectors, we revisit the possibility of a common dark matter origin for multiple excesses across numerous direct detection experiments, with a focus on the excess rates in semicond…
Accurate tight-binding model for twisted bilayer graphene describes topological flat bands without geometric relaxation Open
A major hurdle in understanding the phase diagram of twisted bilayer graphene is the roles of lattice relaxation and electronic structure on isolated band flattening near magic twist angles. Here in this work, the authors develop an accura…
Nanoscale studies of electric field effects on monolayer 1T′-WTe2 Open
Monolayer 1 T′-WTe 2 is a quantum spin Hall insulator with a gapped 2D-bulk and gapless helical edge states persisting to temperatures ~100 K. Despite the far-ranging interest, the magnitude of the bulk gap, the effect of gating on the 2D-…
An accurate tight binding model for twisted bilayer graphene describes topological flat bands without geometric relaxation. Open
A major hurdle in understanding the phase diagram of twisted bilayer graphene (TBLG) are the roles of lattice relaxation and electronic structure on isolated band flattening near magic twist angles. In this work, the authors develop an acc…
Revisiting the Dark Matter Interpretation of Excess Rates in\n Semiconductors Open
In light of recent results from low-threshold dark matter detectors, we\nrevisit the possibility of a common dark matter origin for multiple excesses\nacross numerous direct detection experiments, with a focus on the excess rates\nin semic…
Frontiers of stochastic electronic structure calculations Open
In recent years there has been a rapid growth in the development and application of new stochastic methods in electronic structure. These methods are quite diverse, from many-body wave function techniques in real space or determinant space…
Excited states in variational Monte Carlo using a penalty method Open
In this article, the authors present a technique using variational Monte Carlo to solve for excited states of electronic systems. This technique is based on enforcing orthogonality to lower energy states, which results in a simple variatio…
Electric field effects on the band gap and edge states of monolayer 1T'-WTe2 Open
Monolayer 1T'-WTe2 is a quantum spin Hall insulator with a gapped bulk and gapless helical edge states persisting to temperatures around 100 K. Recent studies have revealed a topological-to-trivial phase transition as well the emergence of…
Excited states in variational Monte Carlo using a penalty method Open
The authors present a technique using variational Monte Carlo to solve for excited states of electronic systems. The technique is based on enforcing orthogonality to lower energy states, which results in a simple variational principle for …
A light weight regularization for wave function parameter gradients in quantum Monte Carlo Open
The parameter derivative of the expectation value of the energy, ∂E/∂p, is a key ingredient in variational Monte Carlo (VMC) wave function optimization methods. In some cases, a naïve estimate of this derivative suffers from an infinite va…