Explicit correlation factors

Johnson, Cole M.; Hirata, So; Ten‐no, Seiichiro

doi:10.1016/j.cplett.2017.02.072

Cited by 16 publications

(17 citation statements)

References 31 publications

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“…Further, it has been pointed out in ref. 17 that F 3 12 represents one of the highly performing correlation factors. Clearly, these points tend to provide some justification for our choice of the two-particle wave function.…”

Section: Single-particle Charge Densities Of Two-electron Systemsmentioning

confidence: 99%

“…Recently, Grünels et al [16] presented an authentic survey on explicitly correlated electronic structure theory with particular emphasis on its application to large systems. On the other hand, Johnson et al [17] made use of the Monte Carlo method to critically examine the performance of different correlation factors as used in the wave functions of small molecules. In ref.…”

Section: Single-particle Charge Densities Of Two-electron Systemsmentioning

confidence: 99%

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Shannon entropies and Fisher information of K-shell electrons of neutral atoms

Sekh¹,

Saha

Talukdar

2018

Physics Letters A

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We represent the two K-shell electrons of neutral atoms by Hylleraas-type wave function which fulfils the exact behavior at the electron-electron and electron-nucleus coalescence points and, derive a simple method to construct expressions for single-particle position-and momentum-space charge densities, ρ(r) and γ(p) respectively. We make use of the results for ρ(r) and γ(p) to critically examine the effect of correlation on bare (uncorrelated) values of Shannon information entropies (S) and of Fisher information (F ) for the K-shell electrons of atoms from helium to neon. Due to inter-electronic repulsion the values of the uncorrelated Shannon position-space entropies are augmented while those of the momentum-space entropies are reduced. The corresponding Fisher information are found to exhibit opposite behavior in respect of this. Attempts are made to provide some plausible explanation for the observed response of S and F to electronic correlation.

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Section: Single-particle Charge Densities Of Two-electron Systemsmentioning

confidence: 99%

Section: Single-particle Charge Densities Of Two-electron Systemsmentioning

confidence: 99%

Shannon entropies and Fisher information of K-shell electrons of neutral atoms

Sekh¹,

Saha

Talukdar

2018

Physics Letters A

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“…Algorithm 1: Hash function that maps any orbital quartet (i, j, k, l) related by permutation symmetry to a unique integer. e hash table is such that each bucket can potentially store 2 15 consecutive key-value pairs. e 15 least signi cant bits of the hash value are removed to give the bucket index [i bucket = hash(i, j, k, l)/2 15 ], and only those 15 bits need to be stored in the bucket for the key storage [hash(i, j, k, l) mod 2 16 ].…”

Section: Storage Of the Two-electron Integralsmentioning

confidence: 99%

“…5 e traditional sequential algorithms of quantum chemistry are currently being redesigned and replaced by parallel equivalents by multiple groups around the world. [6][7][8][9][10][11][12][13][14][15][16][17][18] is has obviously a signi cant in uence on methodological developments. e most iconic example of this move towards parallel-friendly methods is the recently developed full con guration interaction quantum Monte Carlo (FCIQMC) method by Alavi and coworkers.…”

Section: Introductionmentioning

confidence: 99%

Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs

Garniron¹,

Applencourt²,

Gasperich³

et al. 2019

Preprint

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TOC graphical abstract antum chemistry is a discipline which relies heavily on very expensive numerical computations. e scaling of correlated wave function methods lies, in their standard implementation, between O(N 5 ) and O(e N ), where N is proportional to the system size. erefore, performing accurate calculations on chemically meaningful systems requires i) approximations that can lower the computational scaling, and ii) e cient implementations that take advantage of modern massively parallel architectures. P is an open-source programming environment for quantum chemistry specially designed for wave function methods. Its main goal is the development of determinantdriven selected con guration interaction (sCI) methods and multi-reference second-order perturbation theory (PT2). e determinant-driven framework allows the programmer to include any arbitrary set of determinants in the reference space, hence providing greater methodological freedom. e sCI method implemented in P is based on the CIPSI (Con guration Interaction using a Perturbative Selection made Iteratively) algorithm which complements the variational sCI energy with a PT2 correction. Additional external plugins have been recently added to perform calculations with multireference coupled cluster theory and range-separated density-functional theory. All the programs are developed with the IRPF90 code generator, which simpli es collaborative work and the development of new features. P strives to allow easy implementation and experimentation of new methods, while making parallel computation as simple and e cient as possible on modern supercomputer architectures. Currently, the code enables, routinely, to realize runs on roughly 2 000 CPU cores, with tens of millions of determinants in the reference space. Moreover, we have been able to push up to 12 288 cores in order to test its parallel e ciency. In the present manuscript, we also introduce some key new developments: i) a renormalized second-order perturbative correction for e cient extrapolation to the full CI limit, and ii) a stochastic version of the CIPSI selection performed simultaneously to the PT2 calculation at no extra cost.

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“…Hash function that maps any orbital quartet (i, j, k, l) related by permutation symmetry to a unique integer.e hash table is such that each bucket can potentially store 215 consecutive key-value pairs. e 15 least signi cant bits of the hash value are removed to give the bucket index [i bucket = hash(i, j, k, l)/2 15 ], and only those 15 bits need…”

mentioning

confidence: 99%

Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs

Garniron¹,

Applencourt²,

Gasperich³

et al. 2019

Preprint

View full text Add to dashboard Cite

<div> <div> <div> <p> </p><div> <div> <div> <p>Quantum Package is an open-source programming environment for quantum chemistry specially designed for wave function methods. Its main goal is the development of determinant-driven selected configuration interaction (sCI) methods and multi-reference second-order perturbation theory (PT2). The determinant-driven framework allows the programmer to include any arbitrary set of determinants in the reference space, hence providing greater method- ological freedoms. The sCI method implemented in Quantum Package is based on the CIPSI (Configuration Interaction using a Perturbative Selection made Iteratively) algorithm which complements the variational sCI energy with a PT2 correction. Additional external plugins have been recently added to perform calculations with multireference coupled cluster theory and range-separated density-functional theory. All the programs are developed with the IRPF90 code generator, which simplifies collaborative work and the development of new features. Quantum Package strives to allow easy implementation and experimentation of new methods, while making parallel computation as simple and efficient as possible on modern supercomputer architectures. Currently, the code enables, routinely, to realize runs on roughly 2 000 CPU cores, with tens of millions of determinants in the reference space. Moreover, we have been able to push up to 12 288 cores in order to test its parallel efficiency. In the present manuscript, we also introduce some key new developments: i) a renormalized second-order perturbative correction for efficient extrapolation to the full CI limit, and ii) a stochastic version of the CIPSI selection performed simultaneously to the PT2 calculation at no extra cost. </p> </div> </div> </div> </div> </div> </div>

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Explicit correlation factors

Cited by 16 publications

References 31 publications

Shannon entropies and Fisher information of K-shell electrons of neutral atoms

Shannon entropies and Fisher information of K-shell electrons of neutral atoms

Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs

Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs

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