## This content will become publicly available on May 13, 2020

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

## Abstract

Quantum chemistry is a discipline which relies heavily on very expensive numerical computations. The scaling of correlated wave function methods lies, in their standard implementation, between $$\mathcal{O}$$(N ^{5}) and $$\mathcal{O}$$(c ^{N}), where *N* is proportional to the system size. Thus, performing accurate calculations on chemically meaningful systems requires (i) approximations that can lower the computational scaling and (ii) efficient implementations that take advantage of modern massively parallel architectures. 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 multireference 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 methodological freedom. 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. Furthermore, we have been able to push up to 12 288 cores in order to test its parallel efficiency. In the present manuscript, we also present 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.

- Authors:

- Univ. of Toulouse (France). Lab. of Physical Chemistry
- Argonne National Lab. (ANL), Lemont, IL (United States)
- Argonne National Lab. (ANL), Lemont, IL (United States); Univ. of Pittsburgh, PA (United States)
- Sorbonne Univ., Paris (France). Lab. of Theoretical Physics and Chemistry
- Sorbonne Univ., Paris (France). Lab. of Theoretical Physics and Chemistry; Sorbonne Univ., Paris (France). Inst. for Computing and Data Science (ISCD)
- Univ. of Toulouse (France). Calculation in Midi-Pyrénées (CALMIP)
- Aix-Marseille Univ., and CNRS, Marseille (France)

- Publication Date:

- Research Org.:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

- Sponsoring Org.:
- USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division

- OSTI Identifier:
- 1530067

- Grant/Contract Number:
- AC05-00OR22725

- Resource Type:
- Accepted Manuscript

- Journal Name:
- Journal of Chemical Theory and Computation

- Additional Journal Information:
- Journal Volume: 15; Journal Issue: 6; Journal ID: ISSN 1549-9618

- Publisher:
- American Chemical Society

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY

### Citation Formats

```
Garniron, Yann, Applencourt, Thomas, Gasperich, Kevin, Benali, Anouar, Ferté, Anthony, Paquier, Julien, Pradines, Barthélémy, Assaraf, Roland, Reinhardt, Peter, Toulouse, Julien, Barbaresco, Pierrette, Renon, Nicolas, David, Grégoire, Malrieu, Jean-Paul, Véril, Mickaël, Caffarel, Michel, Loos, Pierre-François, Giner, Emmanuel, and Scemama, Anthony. Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs. United States: N. p., 2019.
Web. doi:10.1021/acs.jctc.9b00176.
```

```
Garniron, Yann, Applencourt, Thomas, Gasperich, Kevin, Benali, Anouar, Ferté, Anthony, Paquier, Julien, Pradines, Barthélémy, Assaraf, Roland, Reinhardt, Peter, Toulouse, Julien, Barbaresco, Pierrette, Renon, Nicolas, David, Grégoire, Malrieu, Jean-Paul, Véril, Mickaël, Caffarel, Michel, Loos, Pierre-François, Giner, Emmanuel, & Scemama, Anthony. Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs. United States. doi:10.1021/acs.jctc.9b00176.
```

```
Garniron, Yann, Applencourt, Thomas, Gasperich, Kevin, Benali, Anouar, Ferté, Anthony, Paquier, Julien, Pradines, Barthélémy, Assaraf, Roland, Reinhardt, Peter, Toulouse, Julien, Barbaresco, Pierrette, Renon, Nicolas, David, Grégoire, Malrieu, Jean-Paul, Véril, Mickaël, Caffarel, Michel, Loos, Pierre-François, Giner, Emmanuel, and Scemama, Anthony. Mon .
"Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs". United States. doi:10.1021/acs.jctc.9b00176.
```

```
@article{osti_1530067,
```

title = {Quantum Package 2.0: An Open-Source Determinant-Driven Suite of Programs},

author = {Garniron, Yann and Applencourt, Thomas and Gasperich, Kevin and Benali, Anouar and Ferté, Anthony and Paquier, Julien and Pradines, Barthélémy and Assaraf, Roland and Reinhardt, Peter and Toulouse, Julien and Barbaresco, Pierrette and Renon, Nicolas and David, Grégoire and Malrieu, Jean-Paul and Véril, Mickaël and Caffarel, Michel and Loos, Pierre-François and Giner, Emmanuel and Scemama, Anthony},

abstractNote = {Quantum chemistry is a discipline which relies heavily on very expensive numerical computations. The scaling of correlated wave function methods lies, in their standard implementation, between $\mathcal{O}$(N5) and $\mathcal{O}$(cN), where N is proportional to the system size. Thus, performing accurate calculations on chemically meaningful systems requires (i) approximations that can lower the computational scaling and (ii) efficient implementations that take advantage of modern massively parallel architectures. 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 multireference 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 methodological freedom. 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. Furthermore, we have been able to push up to 12 288 cores in order to test its parallel efficiency. In the present manuscript, we also present 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.},

doi = {10.1021/acs.jctc.9b00176},

journal = {Journal of Chemical Theory and Computation},

number = 6,

volume = 15,

place = {United States},

year = {2019},

month = {5}

}