Publications by categories in reversed chronological order. Generated by jekyll-scholar. Note that several projects from my PhD are still to be published. See my thesis, linked below, (chapters 4 to 6 and appendix A) for more details.
2025
Lifting the spin-restriction in transcorrelated methods
Evelin Martine Corvid Christlmaier, J. Philip Haupt, Pable López Ríos, and 2 more authors
2025
Modular Construction of Jastrow Factors for the Transcorrelated Method
J. Philip Haupt, Maria-Andreea. Filip, Pable López Ríos, and 3 more authors
We explore the applicability of the transcorrelated method to the elements in the second row of the periodic table. We use transcorrelated Hamiltonians in conjunction with full configuration interaction quantum Monte Carlo and coupled cluster techniques to obtain total energies and ionization potentials, investigating their dependence on the nature and size of the basis sets used. Transcorrelation accelerates convergence to the complete basis set limit relative to conventional approaches, and chemically accurate results can generally be obtained with the cc-pVTZ basis, even with a frozen Ne core in the post-Hartree–Fock treatment.
We investigate the optimization of flexible tailored real-space Jastrow factors for use in the transcorrelated (TC) method in combination with highly accurate quantum chemistry methods, such as initiator full configuration interaction quantum Monte Carlo (FCIQMC). Jastrow factors obtained by minimizing the variance of the TC reference energy are found to yield better, more consistent results than those obtained by minimizing the variational energy. We compute all-electron atomization energies for the challenging first-row molecules C2, CN, N2, and O2 and find that the TC method yields chemically accurate results using only the cc-pVTZ basis set, roughly matching the accuracy of non-TC calculations with the much larger cc-pV5Z basis set. We also investigate an approximation in which pure three-body excitations are neglected from the TC-FCIQMC dynamics, saving storage and computational costs, and show that it affects relative energies negligibly. Our results demonstrate that the combination of tailored real-space Jastrow factors with the multi-configurational TC-FCIQMC method provides a route to obtaining chemical accuracy using modest basis sets, obviating the need for basis-set extrapolation and composite techniques.
@article{hauptOptimizing2023,title={{Optimizing {{Jastrow}} Factors for the Transcorrelated Method}},author={Haupt, J. Philip and Hosseini, Seyed Mohammadreza and L\'opez R\'ios, Pablo and Dobrautz, Werner and Cohen, Aron and Alavi, Ali},journal={The Journal of Chemical Physics},volume={158},number={22},pages={224105},year={2023},doi={10.1063/5.0147877},}