Expanding the Design Space of Constraints in Auxiliary-Field Quantum Monte Carlo

Weber, John L.; Vuong, Hung; Friesner, Richard A.; Reichman, David R.

doi:10.1021/acs.jctc.3c00654

Cited by 3 publications

(6 citation statements)

References 30 publications

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“…Similar to previous studies, 42 the imaginary time step for the AFQMC propagation was 0.005 Ha 1− , and the total propagation time was 200 Ha 1− , employing the "comb" algorithm for population control every 20 steps. 43 We used 3312 total walkers, which were initialized with a spinrestricted HF determinant.…”

Section: Methodsmentioning

confidence: 99%

Accurate Quantum Chemical Reaction Energies for Lithium-Mediated Electrolyte Decomposition and Evaluation of Density Functional Approximations

Debnath,

Neufeld,

Jacobson

et al. 2023

J. Phys. Chem. A

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An important concern related to the performance of Li-ion batteries is the formation of a solid electrolyte interphase on the surface of the anode. This film is formed from the decomposition of electrolytes and can have important effects on the stability and performance. Here, we evaluate the decomposition pathway of ethylene carbonate and related organic electrolyte molecules using a series of density functional approximations and correlated wave function (WF) methods, including the coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)] and auxiliary-field quantum Monte Carlo (AFQMC). We find that the transition state barrier associated with ring opening varies widely across different functionals, ranging from 3.01 to 17.15 kcal/mol, which can be compared to the value of 12.84 kcal/mol predicted by CCSD(T). This large variation underscores the importance of benchmarking against accurate WF methods. A performance comparison of all of the density functionals used in this study reveals that the M06-2X-D3 (a meta-hybrid GGA), CAM-B3LYP-D3 (a range-separated hybrid), and B2GP-PLYP-D3 (a double hybrid) perform the best, with average errors of about 1.50−1.60 kcal/ mol compared to CCSD(T). We also compared the performance of the WF methods that are more scalable than CCSD(T), finding that DLPNO−CCSD(T) and phaseless AFQMC with a DFT trial wave function exhibit average errors of 1.38 and 1.74 kcal/mol, respectively.

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Section: Methodsmentioning

confidence: 99%

Accurate Quantum Chemical Reaction Energies for Lithium-Mediated Electrolyte Decomposition and Evaluation of Density Functional Approximations

Debnath,

Neufeld,

Jacobson

et al. 2023

J. Phys. Chem. A

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“…We investigated modifications to the phaseless approximation that significantly reduce the overcorrelation issues frequently encountered in ph-AFQMC, but they did not demonstrate systematic improvement compared to the standard phaseless approximation . However, the phaseless errors can be systematically reduced by improving the trial wave functions ,, or by release constraint techniques. , …”

Section: Theoretical Backgroundmentioning

confidence: 99%

“… 69 However, the phaseless errors can be systematically reduced by improving the trial wave functions 84 , 85 , 104 or by release constraint techniques. 86 , 87 …”

Section: Theoretical Backgroundmentioning

confidence: 99%

“…It has also been successfully applied to excited states , and at finite temperature. − ph-AFQMC exhibits low polynomial scaling ( O false( N 3 false) − O false( N 4 false) ) with system size that can even be reduced to cubic scaling by utilizing tensor hypercontractions, , stochastic resolution of identity, or employing a plane wave basis . The phaseless approximation controls the Fermionic sign problem in ph-AFQMC, however, it also introduces systematic errors that are challenging to control. , Mahajan et al developed a fast method for the evaluation of the local energies for multideterminantal trial wave functions and demonstrated that the phaseless approximation can be systematically improved using better trial wave functions. , Recently, there have been attempts to directly enhance the phaseless approximation. ,, …”

Section: Introductionmentioning

confidence: 99%

“… 84 , 85 Recently, there have been attempts to directly enhance the phaseless approximation. 69 , 86 , 87 …”

Section: Introductionmentioning

confidence: 99%

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Toward Large-Scale AFQMC Calculations: Large Time Step Auxiliary-Field Quantum Monte Carlo

Sukurma,

Schlipf,

Humer

et al. 2024

J. Chem. Theory Comput.

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We report modifications of the ph-AFQMC algorithm that allow the use of large time steps and reliable time step extrapolation. Our modified algorithm eliminates sizeconsistency errors present in the standard algorithm when large time steps are employed. We investigate various methods to approximate the exponential of the one-body operator within the AFQMC framework, distinctly demonstrating the superiority of Krylov methods over the conventional Taylor expansion. We assess various propagators within AFQMC and demonstrate that the Split-2 propagator is the optimal method, exhibiting the smallest timestep errors. For the HEAT set molecules, the time-step extrapolated energies deviate on average by only 0.19 kcal/mol from the accurate small time-step energies. For small water clusters, we obtain accurate complete basis-set binding energies using time-step extrapolation with a mean absolute error of 0.07 kcal/mol compared to CCSD(T). Using large time-step ph-AFQMC for the N 2 dimer, we show that accurate bond lengths can be obtained while reducing CPU time by an order of magnitude.

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Accurate quantum chemical reaction energies for lithium-mediated electrolyte decomposition and evaluation of density functional approximations

Debnath

Neufeld

Jacobson

et al. 2023

Preprint

View full text Add to dashboard Cite

An important concern related to the performance of Li ion batteries is the formation of the solid electrolyte interphase on the surface of the anode. This film is formed from the decomposition of electrolytes and can have important effects on stability and performance. Here, we evaluate the decomposition pathway of ethylene carbonate and related organic electrolyte molecules using a series of density functional approximations and correlated wavefunction (WF) methods, including coupled-cluster theory with single, double, and perturbative triple excitations [CCSD(T)] and auxiliary field quantum Monte Carlo (AFQMC). We find that the transition state barrier associated with ring opening varies widely across different functionals, ranging from 3.00 to 17.15 kcal/mol, which can be compared to the value of 12.84 kcal/mol predicted by CCSD(T).This large variation underscores the importance of benchmarking against accurate WF methods. A performance comparison of all the density functionals used in this study reveals that dispersion-corrected M06-2X (a meta-hybrid GGA), CAMB3LYP (a range-separated hybrid) and B2GP-PLYP (a double-hybrid) perform the best, with average errors of about 1.60 kcal/mol compared to CCSD(T). We also compared the performance of WF methods that are more scalable than CCSD(T), finding that DLPNO-CCSD(T) and phaseless AFQMC with a DFT trial wavefunction exhibit average errors of 1.38 kcal/mol and 1.74 kcal/mol respectively.

show abstract

Expanding the Design Space of Constraints in Auxiliary-Field Quantum Monte Carlo

Cited by 3 publications

References 30 publications

Accurate Quantum Chemical Reaction Energies for Lithium-Mediated Electrolyte Decomposition and Evaluation of Density Functional Approximations

Accurate Quantum Chemical Reaction Energies for Lithium-Mediated Electrolyte Decomposition and Evaluation of Density Functional Approximations

Toward Large-Scale AFQMC Calculations: Large Time Step Auxiliary-Field Quantum Monte Carlo

Accurate quantum chemical reaction energies for lithium-mediated electrolyte decomposition and evaluation of density functional approximations

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