QMCPACK: Advances in the development, efficiency, and application of auxiliary field and real-space variational and diffusion quantum Monte Carlo.

  title={QMCPACK: Advances in the development, efficiency, and application of auxiliary field and real-space variational and diffusion quantum Monte Carlo.},
  author={Paul R. C. Kent and Abdulgani Annaberdiyev and Anouar Benali and M Chandler Bennett and Edgar Josu{\'e} Landinez Borda and Peter W. Doak and Hongxia Hao and Kenneth D. Jordan and Jaron T. Krogel and Ilkka Kyl{\"a}np{\"a}{\"a} and Joonho Lee and Ye Luo and Fionn D. Malone and Cody A Melton and Lubos Mitas and Miguel A. Morales and Eric Neuscamman and Fernando A Reboredo and Brenda M. Rubenstein and Kayahan Saritas and Shiv Upadhyay and Guangming Wang and Shuai Zhang and Luning Zhao},
  journal={The Journal of chemical physics},
  volume={152 17},
We review recent advances in the capabilities of the open source ab initio Quantum Monte Carlo (QMC) package QMCPACK and the workflow tool Nexus used for greater efficiency and reproducibility. The auxiliary field QMC (AFQMC) implementation has been greatly expanded to include k-point symmetries, tensor-hypercontraction, and accelerated graphical processing unit (GPU) support. These scaling and memory reductions greatly increase the number of orbitals that can practically be included in AFQMC… 
Accelerating the convergence of auxiliary-field quantum Monte Carlo in solids with optimized Gaussian basis sets.
This work investigates the use of optimized correlation-consistent Gaussian basis sets for the study of insulating solids with auxiliary-field quantum Monte Carlo (AFQMC) and finds that these optimized basis sets yield the most consistent results as a function of volume.
Systematic comparison and cross-validation of fixed-node diffusion Monte Carlo and phaseless auxiliary-field quantum Monte Carlo in solids
Quantum Monte Carlo (QMC) methods are some of the most accurate methods for simulating correlated electronic systems. We investigate the compatibility, strengths and weaknesses of two such methods,
High Accuracy Transition Metal Effective Cores for the Many-Body Diffusion Monte Carlo Method.
This work shows that a class of differential pseudopotentials, known as pseudo-Hamiltonians, can be constructed for the 3d transition metal atoms, entirely removing the need for any localization scheme in the DMC projector, and produces potentials tailored specifically for real space projector quantum Monte Carlo methods with low error at the many-body level.
Some recent developments in auxiliary-field quantum Monte Carlo for real materials.
A systematic exposition of the key steps of AFQMC is given, closely tracking the framework of a modern software library the authors are developing and a self-consistent constraint for real materials is proposed.
Toward quantum Monte Carlo forces on heavier ions: Scaling properties.
The results predict the practical cost of obtaining forces for a range of materials, such as transition metal oxides where QMC forces have yet to be applied, and underscore the importance of further developing force variance-reduction techniques, particularly for atoms with high Zeff.
Binding and excitations in SixHy molecular systems using quantum Monte Carlo.
The results further corroborate that Si systems, and presumably also related main group IV and V elements of the periodic table (Ge, Sn, etc), exhibit some of the lowest fixed-node biases found in valence-only electronic structure QMC calculations.
Toward a systematic improvement of the fixed-node approximation in diffusion Monte Carlo for solids-A case study in diamond.
A computational method is presented that produces trial wavefunctions with systematically improvable nodes for DMC calculations of periodic solids and indicates a very good error cancellation in carbon diamond between the bulk and atomic total fixed-node energies when using single-determinant nodes.
Towards the ground state of molecules via diffusion Monte Carlo on neural networks
Diffusion Monte Carlo (DMC) based on fixed-node approximation has enjoyed significant devel-opments in the past decades and become one of the go-to methods when accurate ground state energy of molecules
Unbiasing fermionic quantum Monte Carlo with a quantum computer
The results demonstrate a new paradigm of hybrid quantum-classical algorithm, surpassing the popular variational quantum eigensolver in terms of potential towards the first practical quantum advantage in ground state many-electron calculations.


Ab initio computations of molecular systems by the auxiliary‐field quantum Monte Carlo method
The auxiliary‐field quantum Monte Carlo (AFQMC) method provides a computational framework for solving the time‐independent Schrödinger equation in atoms, molecules, solids, and a variety of model
QMCPACK: an open source ab initio quantum Monte Carlo package for the electronic structure of atoms, molecules and solids.
The QMCPACK code is specifically optimized for calculations with large numbers of electrons on the latest high performance computing architectures, including multicore central processing unit and graphical processing unit systems.
Accurate atomic correlation and total energies for correlation consistent effective core potentials.
The results offer a clear benchmark for future high accuracy calculations in a broad variety of correlated wave function methods such as CI and CC as well is in stochastic approaches such as real space sampling QMC.
Frozen-Orbital and Downfolding Calculations with Auxiliary-Field Quantum Monte Carlo.
A generalization of the frozen-orbital approach that downfolds high-energy basis states to a physically relevant low-energy sector, which allows a systematic approach to produce realistic model Hamiltonians to further increase efficiency for extended systems.
Multideterminant Wave Functions in Quantum Monte Carlo.
This Perspective presents a systematic application of large scale multideterminant expansions in QMC and demonstrates the potential of this strategy for systematically reducing the fixed-node error in the wave function and for achieving chemical accuracy in energy predictions.
Auxiliary-field quantum Monte Carlo calculations with multiple-projector pseudopotentials
We have implemented recently developed multiple-projector pseudopotentials into the planewave based auxiliary-field quantum Monte Carlo (pw-AFQMC) method. Multiple-projector pseudopotentials can
Computing the energy of a water molecule using multideterminants: a simple, efficient algorithm.
A method for working with multi-Slater-Jastrow wave functions in QMC codes that is easy to implement, efficient both in computational speed as well as memory, and easily parallelized is described.
Investigation of a Quantum Monte Carlo Protocol To Achieve High Accuracy and High-Throughput Materials Formation Energies.
This work evaluates the use of quantum Monte Carlo (QMC) to calculate material formation energies in a high-throughput environment, and determines a set of accurate pseudopotentials in QMC via a systematic investigation of multiple available pseudopotential libraries.
A new scheme for fixed node diffusion quantum Monte Carlo with pseudopotentials: Improving reproducibility and reducing the trial-wave-function bias.
DLA paves the way to the automation of FN-DMC and its much easier application in large systems by providing good quality results and stable simulations that are slightly more efficient than LA and TM.
Density functional orbitals in quantum Monte Carlo: The importance of accurate densities.
It is found that the accuracy of the density is a strong indicator of the quality of the many-body nodal surface produced by a determinant of the corresponding Kohn-Sham orbitals, and suggests that prioritizing accurate densities in the future development of DFAs would also contribute to the continued improvement of DMC.