Gergely Barcza
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View article: Assessing the Reliability of Truncated Coupled Cluster Wave Function: Estimating the Distance from the Exact Solution
Assessing the Reliability of Truncated Coupled Cluster Wave Function: Estimating the Distance from the Exact Solution Open
A new approach is proposed to assess the reliability of the truncated wave function methods by estimating the deviation from the full configuration interaction (FCI) wave function. While typical multireference diagnostics compare some deri…
View article: Assessing the Reliability of Truncated Coupled Cluster Wavefunction: Estimating the Distance from the Exact Solution
Assessing the Reliability of Truncated Coupled Cluster Wavefunction: Estimating the Distance from the Exact Solution Open
A new approach is proposed to assess the reliability of the truncated wavefunction methods by estimating the deviation from the full configuration interaction (FCI) wavefunction. While typical multireference diagnostics compare some derive…
View article: Identifying high-energy electronic states of NV− centers in diamond
Identifying high-energy electronic states of NV− centers in diamond Open
The negatively charged nitrogen-vacancy center in diamond is a prototype photoluminescent point defect spin qubit with promising quantum technology applications, enabled by its efficient optical spin polarization and readout. Its low-lying…
View article: Carbon-contaminated topological defects in hexagonal boron nitride for quantum photonics
Carbon-contaminated topological defects in hexagonal boron nitride for quantum photonics Open
View article: Identifying high-energy electronic states of NV$^-$ centers in diamond
Identifying high-energy electronic states of NV$^-$ centers in diamond Open
The negatively charged nitrogen-vacancy center in diamond is a prototype photoluminescent point defect spin qubit with promising quantum technology applications, enabled by its efficient optical spin polarization and readout. Its low-lying…
View article: Electronic ladder model harboring <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:msub><mml:mi mathvariant="double-struck">Z</mml:mi><mml:mn>4</mml:mn></mml:msub></mml:mrow></mml:math> parafermions
Electronic ladder model harboring parafermions Open
Parafermions are anyons with the potential for realizing nonlocal qubits that are resilient to local perturbations. Compared with Majorana zero modes, braiding of parafermions implements an extended set of topologically protected quantum g…
View article: Low-symmetry vacancy-related spin qubit in hexagonal boron nitride
Low-symmetry vacancy-related spin qubit in hexagonal boron nitride Open
Point defect qubits in semiconductors have demonstrated their outstanding capabilities for high spatial resolution sensing generating broad multidisciplinary interest. Hexagonal boron nitride (hBN) hosting point defect qubits have recently…
View article: Accurate and convergent energetics of color centers by wavefunction theory
Accurate and convergent energetics of color centers by wavefunction theory Open
Ab initio description of point defects in semiconductors, characterized by in-gap states of significant multideterminant character, presents a longstanding theoretical challenge for density functional theory (DFT) methods. In this study, w…
View article: Carbon-contaminated topological defects in hexagonal boron nitride for quantum photonics
Carbon-contaminated topological defects in hexagonal boron nitride for quantum photonics Open
Topological defects, such as Stone-Wales defects and grain boundaries, are common in 2D materials. In this study, we investigate the intricate interplay of topological defects and carbon contamination in hexagonal boron nitride revealing a…
View article: First-principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter
First-principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter Open
We elaborate on the methodology of computing color centers in periodic and cluster models of hBN. Using first-principles methods, we determined various optical properties of the nitrogen interstitial defect and compared them to experimenta…
View article: A simple electronic ladder model harboring $\mathbb{Z}_4$ parafermions
A simple electronic ladder model harboring $\mathbb{Z}_4$ parafermions Open
Parafermions are anyons with the potential for realizing non-local qubits that are resilient to local perturbations. Compared to Majorana zero modes, braiding of parafermions implements an extended set of topologically protected quantum ga…
View article: Symmetric carbon tetramers forming spin qubits in hexagonal boron nitride
Symmetric carbon tetramers forming spin qubits in hexagonal boron nitride Open
View article: First principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter
First principles theory of the nitrogen interstitial in hBN: a plausible model for the blue emitter Open
Color centers in hexagonal boron nitride (hBN) have attracted considerable attention due to their remarkable optical properties enabling robust room temperature photonics and quantum optics applications in the visible spectral range. On th…
View article: Symmetric carbon tetramers forming chemically stable spin qubits in hBN
Symmetric carbon tetramers forming chemically stable spin qubits in hBN Open
Point defect quantum bits in semiconductors have the potential to revolutionize sensing at atomic scales. Currently, vacancy related defects, such as the NV center in diamond and the VB$^-$ in hexagonal boron nitride (hBN), are at the fore…
View article: Sensitivity of coupled cluster electronic properties on the reference determinant: Can Kohn–Sham orbitals be more beneficial than Hartree–Fock orbitals?
Sensitivity of coupled cluster electronic properties on the reference determinant: Can Kohn–Sham orbitals be more beneficial than Hartree–Fock orbitals? Open
Coupled cluster calculations are traditionally performed over Hartree–Fock reference orbitals (HF‐CC methodology). However, in the literature it has been repeatedly raised whether the use of a Kohn–Sham reference (KS‐CC methodology) might …
View article: Predicting the FCI energy of large systems to chemical accuracy from restricted active space density matrix renormalization group calculations
Predicting the FCI energy of large systems to chemical accuracy from restricted active space density matrix renormalization group calculations Open
We theoretically derive and validate with large scale simulations a remarkably accurate power law scaling of errors for the restricted active space density matrix renormalization group (DMRG-RAS) method [arXiv:2111.06665] in electronic str…
View article: Gépi tanulás a számításos kvantumkémiában
Gépi tanulás a számításos kvantumkémiában Open
View article: Quantum sensor in a single layer van der Waals material
Quantum sensor in a single layer van der Waals material Open
Point defect qubits in semiconductors have demonstrated their outstanding high spatial resolution sensing capabilities of broad multidisciplinary interest. Two-dimensional (2D) semiconductors hosting such sensors have recently opened up ne…
View article: Towards large-scale restricted active space calculations inspired by the Schmidt decomposition
Towards large-scale restricted active space calculations inspired by the Schmidt decomposition Open
We present an alternative, memory-efficient, Schmidt decomposition-based description of the inherently bipartite restricted active space (RAS) scheme, which can be implemented effortlessly within the density matrix renormalization group (D…
View article: Sensitivity of Coupled Cluster Electronic Properties on the Reference Determinant: Can Kohn-Sham Orbitals Be More Beneficial than Hartree-Fock Orbitals?
Sensitivity of Coupled Cluster Electronic Properties on the Reference Determinant: Can Kohn-Sham Orbitals Be More Beneficial than Hartree-Fock Orbitals? Open
Coupled cluster calculations are traditionally performed over Hartree-Fock reference orbitals (HF-CC methodology). However, it has been repeatedly argued in the literature that the use of a Kohn-Sham reference (KS-CC methodology) might res…
View article: Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond
Highly tunable magneto-optical response from magnesium-vacancy color centers in diamond Open
View article: Fermionic systems for quantum information people
Fermionic systems for quantum information people Open
The operator algebra of fermionic modes is isomorphic to that of qubits, the difference between them is twofold: the embedding of subalgebras corresponding to mode subsets and multiqubit subsystems on the one hand, and the parity supersele…
View article: DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride
DMRG on Top of Plane-Wave Kohn–Sham Orbitals: A Case Study of Defected Boron Nitride Open
In this paper, we analyze the numerical aspects of the inherently multi-reference density matrix renormalization group (DMRG) calculations on top of the periodic Kohn-Sham density functional theory (DFT) using the complete active space (CA…
View article: DMRG on top of plane-wave Kohn-Sham orbitals: case study of defected\n boron nitride
DMRG on top of plane-wave Kohn-Sham orbitals: case study of defected\n boron nitride Open
In this paper, we analyze the numerical aspects of the inherently\nmulti-reference density matrix renormalization group (DMRG) calculations on top\nof the periodic Kohn-Sham density functional theory (DFT) using the complete\nactive space …
View article: Ab initio theory of the negatively charged boron vacancy qubit in hexagonal boron nitride
Ab initio theory of the negatively charged boron vacancy qubit in hexagonal boron nitride Open
Highly correlated orbitals coupled with phonons in two-dimension are identified for paramagnetic and optically active boron vacancy in hexagonal boron nitride by first principles methods which are responsible for recently observed opticall…
View article: Symmetric single-impurity Kondo model on a tight-binding chain: Comparison of analytical and numerical ground-state approaches
Symmetric single-impurity Kondo model on a tight-binding chain: Comparison of analytical and numerical ground-state approaches Open
We analyze the ground-state energy, local spin correlation, impurity spin\npolarization, impurity-induced magnetization, and corresponding zero-field\nsusceptibilities of the symmetric single-impurity Kondo model on a\ntight-binding chain …
View article: Ab initio theory of negatively charged boron vacancy qubit in hBN
Ab initio theory of negatively charged boron vacancy qubit in hBN Open
Highly correlated orbitals coupled with phonons in two-dimension are identified for paramagnetic and optically active boron vacancy in hexagonal boron nitride by first principles methods which are responsible for recently observed opticall…
View article: Ground-state properties of the symmetric single-impurity Anderson model on a ring from density-matrix renormalization group, Hartree-Fock, and Gutzwiller theory
Ground-state properties of the symmetric single-impurity Anderson model on a ring from density-matrix renormalization group, Hartree-Fock, and Gutzwiller theory Open
We analyze the ground-state energy, magnetization, magnetic susceptibility,\nand Kondo screening cloud of the symmetric single-impurity Anderson model\n(SIAM) that is characterized by the band width $W$, the impurity interaction\nstrength …
View article: Molekulákba kódolt kvantuminformáció: átmenetifém-klaszterek elektronszerkezete
Molekulákba kódolt kvantuminformáció: átmenetifém-klaszterek elektronszerkezete Open
View article: Towards a multiconfigurational method of increments
Towards a multiconfigurational method of increments Open
The method of increments (MoI) allows one to successfully calculate cohesive energies of bulk materials with high accuracy, but it encounters difficulties when calculating dissociation curves. The reason is that its standard formalism is b…