58 citations · 81 across the 9 of their papers we have counts for
10 papers
Ab Initio Approach for Quantum Magnets with Coupled Cluster and Transcorrelation
Kristoffer Simula, Nikolay A. Bogdanov, Olle Gunnarsson +2
The nearest-neighbour exchange coupling is the simplest ingredient of model Hamiltonians used to understand magnetism in real materials. Nevertheless, its ab initio determina…
ElemCo.jl: A Julia package for electron-correlation methods
Daniel Kats, Charlotte Rickert, Thomas Schraivogel +3
We present ElemCo.jl, an open-source Julia package for molecular electronic structure and properties calculations with a particular emphasis on Coupled Cluster and Distinguishable…
Compression of virtual spaces in transcorrelated methods via singular value decomposition: application to the G2 set
Yifan Cheng, Kristoffer Simula, Johannes Hauskrecht +3
We introduce a new singular-value-decomposition-based scheme for constructing small virtual spaces out of large basis sets for transcorrelated (TC) calculations, termed SVD-TC. Thi…
An Additive Reference Correction Scheme for the Transcorrelated Method
Johannes Hauskrecht, Kristoffer Simula, Yifan Cheng +3
We introduce an additive reference correction for the transcorrelated (TC) method and its three-body mean-field approximation (xTC), to improve energy differences computed in small…
A Transcorrelated Wave-Function Framework for Solids: An Application to Bulk and Defected Silicon
Kristoffer Simula, Johannes Hauskrecht, Evelin Martine Corvid Christlmaier +4
Accurate wave-function descriptions of pristine and defected solids remain challenging due to the simultaneous presence of finite-size, basis-set, and correlation errors. While emb…
Transcorrelated Theory for Transition Metal Atoms
Kristoffer Simula, Maria-Andreea Filip, Ali Alavi
We benchmark ionisation and excitation energies of transition-metal atoms Sc-Zn with a transcorrelated Hamiltonian combined with pseudopotentials. The similarity transformed Hamilt…
Transcorrelated Theory with Pseudopotentials
Kristoffer Simula, Evelin Martine Corvid Christlmaier, Maria-Andreea Filip +4
The transcorrelated (TC) method performs a similarity transformation on the electronic Schrödinger equation via Jastrow factorization of the wave function. This has demonstrated si…
Quantum Monte Carlo study of Doppler broadening of positron annihilation radiation in semiconductors and insulators
Kristoffer Simula, Jan Härkönen, Iuliia Zhelezova +3
Positron annihilation in solid state matter can be utilized to detect and identify open-volume defects. The momentum distribution of the annihilation radiation is an important obse…
Calculation of the energies of the multideterminant states of the nitrogen vacancy center in diamond with quantum Monte Carlo
Kristoffer Simula, Ilja Makkonen
Certain point defects in solids can efficiently be used as qubits for applications in quantum technology. They have spin states that are initializable, readable, robust, and can be…
Split Ga vacancies and the unusually strong anisotropy of positron annihilation spectra in -GaO
Antti Karjalainen, Vera Prozheeva, Kristoffer Simula +4
We report a systematic first principles study on positron annihilation parameters in the -GaO lattice and Ga mono-vacancy defects complemented with orientation-dependent…