# Improved Fast Randomized Iteration Approach to Full Configuration Interaction.

@article{Greene2020ImprovedFR, title={Improved Fast Randomized Iteration Approach to Full Configuration Interaction.}, author={Samuel M. Greene and Robert J. Webber and Jonathan Weare and Timothy C. Berkelbach}, journal={Journal of chemical theory and computation}, year={2020} }

We present three modifications to our recently introduced fast randomized iteration method for full configuration interaction (FCI-FRI) and investigate their effects on the method's performance for Ne, H2O, and N2. The initiator approximation, originally developed for full configuration interaction quantum Monte Carlo, significantly reduces statistical error in FCI-FRI when few samples are used in compression operations, enabling its application to larger chemical systems. The semi-stochastic…

## 8 Citations

### Approximating Matrix Eigenvalues by Subspace Iteration with Repeated Random Sparsification

- Computer ScienceSIAM J. Sci. Comput.
- 2022

This work presents a general approach to extending Iterative random sparsification methods for the estimation of multiple eigenvalues and demonstrates its performance for several benchmark problems in quantum chemistry.

### Full Configuration Interaction Excited-State Energies in Large Active Spaces from Randomized Subspace Iteration

- Mathematics
- 2022

from Randomized Subspace Iteration Samuel M. Greene,1 Robert J. Webber,2, a) James E. T. Smith,3 Jonathan Weare,2, b) and Timothy C. Berkelbach1, 3, c) 1)Department of Chemistry, Columbia University,…

### Full Configuration Interaction Excited-State Energies in Large Active Spaces from Subspace Iteration with Repeated Random Sparsification.

- ChemistryJournal of chemical theory and computation
- 2022

We present a stable and systematically improvable quantum Monte Carlo (QMC) approach to calculating excited-state energies, which we implement using our fast randomized iteration method for the full…

### Polaron-Depleton Transition in the Yrast Excitations of a One-Dimensional Bose Gas with a Mobile Impurity

- PhysicsCondensed Matter
- 2022

We present exact numerical data for the lowest-energy momentum eigenstates (yrast states) of a repulsive spin impurity in a one-dimensional Bose gas using full configuration interaction quantum Monte…

### Approximating matrix eigenvalues by randomized subspace iteration

- Computer ScienceArXiv
- 2021

This work presents a general approach to extending Randomized iterative methods for the estimation of multiple eigenvalues and demonstrates its performance for problems in quantum chemistry with matrices as large as 28 million by 28 million.

### Stochastic differential equation approach to understanding the population control bias in full configuration interaction quantum Monte Carlo

- Geology
- 2021

We investigate a systematic statistical bias found in full conﬁguration quantum Monte Carlo (FCIQMC) that originates from controlling a walker population with a ﬂuctuating shift parameter. This bias…

### The Shape of FCI to Come

- Physics
- 2020

A perspective on what the future holds for full configuration interaction (FCI) theory is presented, with an emphasis on conceptual rather than technical details, and a number of general observations on the merits offered by the state-of-the-art alongside some of the challenges still faced to this day are conveyed.

### Ground and excited state first-order properties in many-body expanded full configuration interaction theory.

- ChemistryThe Journal of chemical physics
- 2020

The recently proposed many-body expanded full configuration interaction (MBE-FCI) method is extended to excited states and static first-order properties different from total, ground state correlation energies to admit a wide range of future applications by means of many- body expanded treatments of electron correlation.

## References

SHOWING 1-10 OF 68 REFERENCES

### Unbiasing the initiator approximation in full configuration interaction quantum Monte Carlo.

- PhysicsThe Journal of chemical physics
- 2019

It is demonstrated that this algorithm shows rapid convergence to the FCI limit with respect to the walker number and largely removes the dependence of the algorithm on the initiator threshold, enabling highly accurate results to be obtained even with large values of the threshold.

### Beyond Walkers in Stochastic Quantum Chemistry: Reducing Error using Fast Randomized Iteration.

- PhysicsJournal of chemical theory and computation
- 2019

Performing ground-state calculations on five small molecules at fixed cost, it is found that the systematic FRI scheme is about 10 to 60 times more statistically efficient than the multinomial FRI scheme, which is in turn about 1.4 to 200 times more statistical efficient than FCIQMC.

### Quantum simulation of strongly correlated condensed matter systems

- Physics
- 2018

We review recent experimental and theoretical progress in realizing and simulating many-body phases of ultracold atoms in optical lattices, which gives access to analog quantum simulations of…

### The iterative calculation of a few of the lowest eigenvalues and corresponding eigenvectors of large real-symmetric matrices

- Mathematics
- 1975

### Numerical study of the two-dimensional Heisenberg model using a Green function Monte Carlo technique with a fixed number of walkers

- Physics
- 1998

We describe in detail a simple and efficient Green function Monte Carlo technique for computing both the ground state energy and the ground state properties by the ``forward walking'' scheme. The…

### Monte Carlo Methods In Ab Initio Quantum Chemistry

- Chemistry, Physics
- 1994

Review of ab initio quantum chemistry introduction to Monte Carlo methods the variational Monte Carlo method quantum Monte Carlo exact Green's function methods released node methods excited states…

### Further limit theorems

- Mathematics
- 1960

In this section we give several more limit theorems about S n including the central limit theorem and the law of the iterated logarithm. The state space I will now be assumed to be positive class, in…