Exact two-component Hamiltonians for relativistic quantum chemistry: Two-electron picture-change corrections made simple

• URL: http://arxiv.org/abs/2204.03977v1
• Date: Fri, 8 Apr 2022 10:11:29 GMT
• Title: Exact two-component Hamiltonians for relativistic quantum chemistry: Two-electron picture-change corrections made simple
• Authors: Stefan Knecht, Michal Repisky, Hans J{\o}rgen Aagaard Jensen, Trond Saue
• Abstract summary: We present two matrix-algebraic approaches to correct textitand spin-orbit two-electron picture-change effects (PCE) arising within an exact two-component (X2C) Hamiltonian framework. We assess the numerical performance of these PCE correction models on spinor energies of group-18 and group-16 diatomic molecules. We are confident that our (e)amfX2C PCE correction models constitute a fundamental milestone towards a universal and reliable relativistic two-component quantum chemical approach.
• Score: 0.0
• License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
• Abstract: Based on self-consistent field (SCF) atomic mean-field (amf) quantities, we present two simple, yet computationally efficient and numerically accurate matrix-algebraic approaches to correct both scalar-relativistic \textit{and} spin-orbit two-electron picture-change effects (PCE) arising within an exact two-component (X2C) Hamiltonian framework. Both approaches, dubbed amfX2C and e(xtended)amfX2C, allow us to uniquely tailor PCE corrections to mean-field models, $viz.$ Hartree-Fock or Kohn-Sham DFT, in the latter case also avoiding the need of a point-wise calculation of exchange-correlation PCE corrections. We assess the numerical performance of these PCE correction models on spinor energies of group-18 (closed-shell) and group-16 (open-shell) diatomic molecules, achieving a consistent $\approx\!10^{-5}$ Hartree accuracy compared to reference four-component data. Additional tests include SCF calculations of molecular properties such as absolute contact density and contact density shifts in copernicium fluoride compounds (CnF$_{n}$, n=2,4,6), as well as equation-of-motion coupled cluster calculations of X-ray core ionization energies of $5d$ and $6d$-containing molecules, where we observe an excellent agreement with reference data. To conclude, we are confident that our (e)amfX2C PCE correction models constitute a fundamental milestone towards a universal and reliable relativistic two-component quantum chemical approach, maintaining the accuracy of the parent four-component one at a fraction of its computational cost.

Related papers

• Learning Equivariant Non-Local Electron Density Functionals [51.721844709174206]
  We introduce Equivariant Graph Exchange Correlation (EG-XC), a novel non-local XC functional based on equivariant graph neural networks. EG-XC combines semi-local functionals with a non-local feature density parametrized by an equivariant nuclei-centered point cloud representation. We find EG-XC to accurately reconstruct gold-standard' CCSD(T) energies on MD17.
  arXiv  Detail & Related papers  (2024-10-10T14:31:45Z)
• MP2-based composite extrapolation schemes can predict core-ionization energies for first-row elements with coupled-cluster level accuracy [0.0]
  X-ray photoelectron spectroscopy (XPS) measures core-electron binding energies (CEBEs) to reveal element-specific insights into chemical environment and bonding. This work systematically investigates basis set selection for extrapolation to the complete basis set (CBS) limit of CEBEs. An alternative composite scheme using $Delta$MP2 in a large basis corrected by $Delta$CC-$Delta$MP2 difference in a small basis can quantitatively recover optimally extrapolated $Delta$CC CEBEs within 0.02 eV.
  arXiv  Detail & Related papers  (2024-03-11T01:27:57Z)
• Enhancing the Electron Pair Approximation with Measurements on Trapped Ion Quantum Computers [7.1240576597319825]
  We introduce reduced density matrix (RDM) based second order theory (PT2) as an energetic correction to electron pair approximation. The new approach takes into account the broken-pair energy contribution that is missing in pair-correlated electron simulations. On two generations of the IonQ's trapped ion quantum computers, Aria and Forte, we find that unlike the VQE energy, the PT2 energy correction is highly noise-resilient.
  arXiv  Detail & Related papers  (2023-12-09T01:13:46Z)
• Modeling Non-Covalent Interatomic Interactions on a Photonic Quantum Computer [50.24983453990065]
  We show that the cQDO model lends itself naturally to simulation on a photonic quantum computer. We calculate the binding energy curve of diatomic systems by leveraging Xanadu's Strawberry Fields photonics library. Remarkably, we find that two coupled bosonic QDOs exhibit a stable bond.
  arXiv  Detail & Related papers  (2023-06-14T14:44:12Z)
• Photonic Quantum Computing For Polymer Classification [62.997667081978825]
  Two polymer classes visual (VIS) and near-infrared (NIR) are defined based on the size of the polymer gaps. We present a hybrid classical-quantum approach to the binary classification of polymer structures.
  arXiv  Detail & Related papers  (2022-11-22T11:59:52Z)
• Simulating Spin-Orbit Coupling With Quasidegenerate N-Electron Valence Perturbation Theory [77.34726150561087]
  We present the first implementation of spin-orbit coupling effects in SO-QDNEVPT2. The accuracy of these methods is tested for the group 14 and 16 hydrides, 3d and 4d transition metal ions, and two actinide dioxides.
  arXiv  Detail & Related papers  (2022-11-11T20:03:37Z)
• Graph neural networks for fast electron density estimation of molecules, liquids, and solids [0.0]
  We present a machine learning framework for the prediction of $rho(vecr)$. The model is tested across multiple data sets of molecules (QM9), liquid ethylene carbonate electrolyte (EC) and LixNiyMnzCo (1-y-z)O2 lithium ion battery cathodes (NMC)
  arXiv  Detail & Related papers  (2021-12-01T16:57:31Z)
• Improving the Accuracy of the Variational Quantum Eigensolver for Molecular Systems by the Explicitly-Correlated Perturbative [2]-R12-Correction [0.0]
  We provide an integration of the universal, perturbative explicitly correlated [2]$_textR12$-correction in the context of the Variational Quantum Eigensolver (VQE) This approach is able to increase the accuracy of the underlying reference method significantly while requiring no additional quantum resources.
  arXiv  Detail & Related papers  (2021-10-13T15:52:01Z)
• Benchmarking adaptive variational quantum eigensolvers [63.277656713454284]
  We benchmark the accuracy of VQE and ADAPT-VQE to calculate the electronic ground states and potential energy curves. We find both methods provide good estimates of the energy and ground state. gradient-based optimization is more economical and delivers superior performance than analogous simulations carried out with gradient-frees.
  arXiv  Detail & Related papers  (2020-11-02T19:52:04Z)
• A multiconfigurational study of the negatively charged nitrogen-vacancy center in diamond [55.58269472099399]
  Deep defects in wide band gap semiconductors have emerged as leading qubit candidates for realizing quantum sensing and information applications. Here we show that unlike single-particle treatments, the multiconfigurational quantum chemistry methods, traditionally reserved for atoms/molecules, accurately describe the many-body characteristics of the electronic states of these defect centers.
  arXiv  Detail & Related papers  (2020-08-24T01:49:54Z)
• Predicting molecular dipole moments by combining atomic partial charges and atomic dipoles [3.0980025155565376]
  "MuML" models are fitted together to reproduce molecular $boldsymbolmu$ computed using high-level coupled-cluster theory. We demonstrate that the uncertainty in the predictions can be estimated reliably using a calibrated committee model.
  arXiv  Detail & Related papers  (2020-03-27T14:35:37Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.