<scp>Psi4</scp> 1.1: An Open-Source Electronic Structure Program Emphasizing Automation, Advanced Libraries, and Interoperability

Parrish, Robert M.; Burns, Lori A.; Smith, Daniel G. A.; Simmonett, Andrew C.; DePrince, A. Eugene; Hohenstein, Edward G.; Bozkaya, Uğur; Sokolov, Alexander Yu.; Remigio, Roberto Di; Richard, Ryan M.; Gonthier, Jérôme F.; James, Andrew M.; McAlexander, Harley R.; Kumar, Ashutosh; Saitow, Masaaki; Wang, Xiao; Pritchard, Benjamin P.; Verma, Prakash; Schaefer, Henry F.; Patkowski, Konrad; King, Rollin A.; Valeev, Edward F.; Evangelista, Francesco A.; Turney, Justin M.; Crawford, T. Daniel; Sherrill, C. David

doi:10.1021/acs.jctc.7b00174

Cited by 1,124 publications

(934 citation statements)

References 168 publications

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“…[53] First, as eries of constant-volume optimizations was carried out with the positions of atoms allowed to change freely.T hen as ingle-point calculation was performed with the integration in the first Brillouin zone carried out according to the tetrahedron method with Blçchl corrections. [54] All SAPT, [55] Hartree-Fock (HF), and MP2 calculations were performed in the Psi4 program [56] by using the aug-cc-pVTZ basis set [57,58] and appropriate auxiliary fitting basis sets. [59,60] The geometries of As 4 O 6 molecules at different pressures for SAPT0, HF,a nd MP2 calculations were taken from Ref.…”

Section: Methodsmentioning

confidence: 99%

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

et al. 2018

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Investigations into the helium permeation of arsenolite, the cubic, molecular arsenic(III) oxide polymorph As O , were carried out to understand how and why arsenolite helium clathrate As O ⋅2 He is formed. High-pressure synchrotron X-ray diffraction experiments on arsenolite single crystals revealed that the permeation of helium into nonporous arsenolite depends on the time for which the crystal is subjected to high pressure and on the crystal history. The single crystal was totally transformed into As O ⋅2 He within 45 h under 5 GPa. After release of the pressure, arsenolite was recovered and a repeated increase in pressure up to 3 GPa led to practically instant As O ⋅2 He formation. However, when a pristine arsenolite single crystal was quickly subjected to a pressure of 13 GPa, no helium permeation was observed at all. No neon permeation was observed in analogous experiments. Quantum mechanical computations indicate that there are no specific attractive interactions between He atoms and As O molecules at the distances observed in the As O ⋅2 He crystal structure. Detailed analysis of As O molecular structure changes has shown that the introduction of He into the arsenolite crystal lattice significantly reduces molecular deformations by decreasing the anisotropy of stress exerted on the As O molecules. This effect and the pΔV term, rather than any specific As⋅⋅⋅He binding, are the driving forces for the formation As O ⋅2 He.

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Section: Methodsmentioning

confidence: 99%

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

et al. 2018

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“…The theory presented here, along with the uncompressed CC3 method, was implemented in a locally modified version of the Gamess program package . The validity of the new implementation was verified by comparing with independent routines available in the Psi 4 program package . On‐the‐fly and semi‐direct variants of the Golub‐Kahan bidiagonalization scheme, as described earlier in the text, are available.…”

Section: Efficient Svd Of T3 Amplitudesmentioning

confidence: 99%

Efficient singular‐value decomposition of the coupled‐cluster triple excitation amplitudes

Lesiuk

2019

J Comput Chem

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We demonstrate a novel technique to obtain singular‐value decomposition (SVD) of the coupled‐cluster triple excitations amplitudes, tijkabc. The presented method is based on the Golub‐Kahan bidiagonalization strategy and does not require tijkabc to be stored. The computational cost of the method is comparable to several coupled cluster singles and doubles (CCSD) iterations. Moreover, the number of singular vectors to be found can be predetermined by the user and only those singular vectors which correspond to the largest singular values are obtained at convergence. We show how the subspace of the most important singular vectors obtained from an approximate triple amplitudes tensor can be used to solve equations of the CC3 method. The new method is tested for a set of small and medium‐sized molecular systems in basis sets ranging in quality from double‐ to quintuple‐zeta. It is found that to reach the chemical accuracy (≈1 kJ/mol) in the total CC3 energies as little as 5 − 15% of SVD vectors are required. This corresponds to the compression of the tijkabc amplitudes by a factor of about 0.0001 − 0.005. Significant savings are obtained also in calculation of interaction energies or rotational barriers, as well as in bond‐breaking processes. © 2019 Wiley Periodicals, Inc.

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“…All DFT and TD-DFT calculations were performed with Gaussian 16 b.01, [52] CASSCF and CASPT2 calculations with MOLCAS, [53] ADC(2), ADC(3) and EOM-CCSD [54][55][56] with Qchem, [57] CC2 with Psi4 [58] and CI-MRPT2 with BALOO. [41] NEVPT2 results are obtained with computational codes developed at the University of Ferrara.…”

Section: Computational Detailsmentioning

confidence: 99%

The Intriguing Case of the One‐Photon and Two‐Photon Absorption of a Prototypical Symmetric Squaraine: Comparison of TDDFT and Wave‐Function Methods

et al. 2019

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We face the challenging description of the excited states responsible for one photon (OPA) and two photon (TPA) absorption in squaraine dyes, adopting both time-dependent density functional theory and a large variety of post Hartree Fock methods, including coupled cluster and adiabatic diagrammatic construction methods (ADC, to the second and third order), symmetry adapted cluster configuration interaction (CI), CASSCF including second-order perturbative corrections (PT2) with standard CASPT2 recipe and according to n-electron valence PT2 (NEVPT2) approach, and an additional multireference CI with PT2 corrections (CI-MRPT2). We selected a small prototypical symmetric squaraine dye for which these accurate computations are feasible and experimental data are available.We show that while all methods reasonably reproduce the OPA spectrum, an acceptable description and assignment of the states responsible for TPA is only possible through ADC(3) and multireference calculations, due to the strong involvement of double-excitations. The nature of ground state and OPA and TPA states is investigated with a rigorous reading of the CASSCF wavefunctions in terms of localized molecular orbitals on the donor and acceptor fragments, showing that these states arise from a balance of many different contributions including biradical configurations, local excitations and charge-transfer states where both side aromatic rings and the carbonyls of the squarylium moiety act as donors.[a] Dr.

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Psi4 1.1: An Open-Source Electronic Structure Program Emphasizing Automation, Advanced Libraries, and Interoperability

Cited by 1,124 publications

References 168 publications

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

How and Why Does Helium Permeate Nonporous Arsenolite Under High Pressure?

Efficient singular‐value decomposition of the coupled‐cluster triple excitation amplitudes

The Intriguing Case of the One‐Photon and Two‐Photon Absorption of a Prototypical Symmetric Squaraine: Comparison of TDDFT and Wave‐Function Methods

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