scholarly journals Seminumerical calculation of the Hartree-Fock exchange matrix: Application to two-component procedures and efficient evaluation of local hybrid density functionals

2012 ◽  
Vol 33 (7) ◽  
pp. 810-816 ◽  
Author(s):  
Philipp Plessow ◽  
Florian Weigend
Keyword(s):  
Density Functionals ◽  
Hartree Fock ◽  
Matrix Application ◽  
Two Component ◽  
Exchange Matrix

scholarly journals The crystalline structure of SrRuO3: Application of hybrid scheme to the density functionals revised for solids

2017 ◽  
Vol 57 (2) ◽  
Author(s):  
Šarūnas Masys ◽  
Valdas Jonauskas
Keyword(s):  
Crystalline Structure ◽  
Density Functional ◽  
Theoretical Modelling ◽  
Density Functionals ◽  
Hybrid Scheme ◽  
Generalized Gradient ◽  
Functional Theory ◽  
Hartree Fock ◽  
Hybrid Density Functional ◽  
Theory Scheme

The crystalline structure of ground-state orthorhombic SrRuO3 is reproduced by applying the hybrid density functional theory scheme to the functionals based on the revised generalized-gradient approximations for solidstate calculations. The amount of Hartree–Fock (HF) exchange energy is varied in the range of 5–20% in order to systematically ascertain the optimum value of HF mixing which in turn ensures the best correspondence to the experimental measurements. Such investigation allows one to expand the set of tools that could be used for the efficient theoretical modelling of, for example, only recently stabilized phases of SrRuO3, helping to resolve issues emerging for the experimentalists.

Hartree-Fock energy-density functionals generated by local-scaling transformations: Applications to first-row atoms

1997 ◽  
Vol 107 (17) ◽  
pp. 6722-6731 ◽  
Author(s):  
R. López-Boada ◽  
E. V. Ludeña ◽  
V. Karasiev ◽  
R. Pino
Keyword(s):  
Energy Density ◽  
Density Functionals ◽  
Local Scaling ◽  
Hartree Fock

scholarly journals Approximate singly excited states from a two-component Hartree-Fock reference

2015 ◽  
Vol 143 (14) ◽  
pp. 144106 ◽  
Author(s):  
Joshua J. Goings ◽  
Feizhi Ding ◽  
Ernest R. Davidson ◽  
Xiaosong Li
Keyword(s):  
Excited States ◽  
Hartree Fock ◽  
Two Component

Linear scaling computation of the Hartree–Fock exchange matrix

1996 ◽  
Vol 105 (7) ◽  
pp. 2726-2734 ◽  
Author(s):  
Eric Schwegler ◽  
Matt Challacombe
Keyword(s):  
Linear Scaling ◽  
Hartree Fock ◽  
Exchange Matrix

scholarly journals The Ranked-Orbital Approach to Selecting Active Spaces

2021 ◽  
Author(s):  
Daniel King ◽  
Laura Gagliardi
Keyword(s):  
High Throughput ◽  
Large Scale ◽  
Pair Interaction ◽  
Excitation Energies ◽  
Selection Scheme ◽  
Active Space ◽  
Hartree Fock ◽  
The Past ◽  
Exchange Matrix ◽  
Multireference Methods

The past decade has seen a great increase in the application of high-throughput computation to a variety of important problems in chemistry. However, one area which has been resistant to the high-throughput approach is multireference wave function methods, in large part due to the technicalities of setting up these calculations and in particular the not always intuitive challenge of active space selection. As we look towards a future of applying high-throughput computation to all areas of chemistry, it is important to prepare these methods for large-scale automation. Here, we propose a ranked-orbital approach to selecting active spaces with the goal of standardizing multireference methods for high-throughput computation. This method allows for the meaningful comparison of different active space selection schemes and orbital localizations, and we demonstrate the utility of this approach across 1120 multireference calculations for the excitation energies of small molecules. Additionally, we propose our own active space selection scheme that estimates the importance of an orbital for the active space through a pair-interaction framework from orbital energies and features of the Hartree-Fock exchange matrix. We call this new scheme the "Approximate Pair Coefficient" (APC) method and it performs quite well for the test systems presented

scholarly journals Relativistic Brueckner-Hartree-Fock Theory in Infinite Nuclear Matter

2021 ◽  
Vol 252 ◽  
pp. 02001
Author(s):  
Peter Ring ◽  
Sibo Wang ◽  
Qiang Zhao ◽  
Jie Meng
Keyword(s):  
Nuclear Matter ◽  
Complete Solution ◽  
Negative Energy ◽  
The Other ◽  
Positive Energy ◽  
Density Functionals ◽  
Matrix Elements ◽  
Hartree Fock ◽  
Microscopic Derivation ◽  
Covariant Density

On the way of a microscopic derivation of covariant density functionals, the first complete solution of the relativistic Brueckner-Hartree-Fock (RBHF) equations is presented for symmetric nuclear matter. In most of the earlier investigations, the G-matrix is calculated only in the space of positive energy solutions. On the other side, for the solution of the relativistic Hartree-Fock (RHF) equations, also the elements of this matrix connecting positive and negative energy solutions are required. So far, in the literature, these matrix elements are derived in various approximations. We discuss solutions of the Thompson equation for the full Dirac space and compare the resulting equation of state with those of earlier attempts in this direction.

scholarly journals Covariant density functional theory: predictive power and first attempts of a microscopic derivation

2018 ◽  
Vol 178 ◽  
pp. 02001
Author(s):  
Peter Ring
Keyword(s):  
Nuclear Matter ◽  
Density Functional ◽  
Predictive Power ◽  
Tensor Force ◽  
Density Functionals ◽  
Functional Theory ◽  
Hartree Fock ◽  
Microscopic Derivation ◽  
Nuclear Systems ◽  
Covariant Density

We discuss systematic global investigations with modern covariant density functionals. The number of their phenomenological parameters can be reduced considerable by using microscopic input from ab-initio calculations in nuclear matter. The size of the tensor force is still an open problem. Therefore we use the first full relativistic Brueckner-Hartree-Fock calculations in finite nuclear systems in order to study properties of such functionals, which cannot be obtained from nuclear matter calculations.

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