Themed collection Correlated electronic structure

We develop a spinless formulation of AC0 based on the Dyall Hamiltonian and provide a detailed comparison between AC0 and NEVPT2 approaches.

QIT offers a comprehensive toolbox for electron correlation analysis, and development of new methods for solving the electronic problem. QChem in turn provides a platform to realize quantum technology, and supplies the valuable resource of quantum entanglement in molecules.

Accurate electronic-structure calculations for molecules and solids with heavy elements require an interplay of electronic correlations and relativistic effects. However, this tedious task poses problems for the existing quantum chemistry machinery.

We present a discussion of explicit correlation approaches which address the nagging problem of dealing with static and dynamic electron correlation in multi-configurational active-space approaches.

In this work, we extend the ghost Gutzwiller (gGut) framework to strongly correlated molecules, for which it holds special promise.

We present a series of algorithmic changes that can be used to accelerate the MR-CCMC algorithm in particular and QMC algorithms in general.

A detailed classification scheme for the excited states of diradicals is presented highlighting the connections between the states of closed-shell and open-shell molecules.

Combining the transcorrelated method with adaptive quantum ansätze in the context of variational quantum imaginary time evolution significantly reduces the necessary circuit depth and width for performing accurate quantum chemistry using quantum computers.

The use of overlapping atom-centered impurity fragments in recently-developed ab initio all-orbital DMFT, where all local orbitals within the impurity are treated with high-level quantum chemistry impurity solvers, is investigated.

We present the first application to real molecular systems of the recently proposed linear-response theory for the density-based basis-set correction method [J. Chem. Phys., 158, 234107 (2023)].

We present a combination of the bi-orthogonal orbital optimisation framework with the recently introduced xTC version of transcorrelation.

We aim not to define the term strong correlation once and for all, but to highlight one possibility that is both rigorously defined and physically transparent, and remains so in reference to molecules and quantum lattice models.

A detailed derivation of cumulant Green’s function methods is presented, and the performance of this scheme in describing outer-valence quasiparticle and satellite energies of molecular systems is explored.

Incommensurate magnetic structure of Cu₂OCl₂, determined by a CAS + DDCI evaluation of the magnetic low energy Hamiltonian, and a Monte-Carlo determination of its ground state.

Accurate force and stress calculations for solids are achieved with a neural-network wavefunction.

Numerical results demonstrate that highly accurate energies can be achieved with a compact quantum-compatible ansatz for both weak and strong correlation in the Hubbard model, and the repulsive pairing Hamiltonian.

In this contribution, the challenges associated with the long-term development of general-purpose quantum chemical software packages are discussed and illustrated with the example of the ORCA package.

Local correlation allows accurate periodic CCSD(T) calculations to be efficiently performed for molecules on realistic surfaces with large basis sets, yielding accurate adsorption energies and vibrational frequencies.