Education & Training

Ph. D. Theoretical Chemistry (2022)
University of Munich (LMU)
Development of Highly Efficient and Accurate Real-Space Integration Methods for Hartree-Fock and Hybrid Density Functional Calculations
DOI: 10.5282/edoc.30648
Advisor: Christian Ochsenfeld

Master of Science in Chemistry (2017)
University of Munich (LMU)
Density Functionals with Dependence on the Exact Exchange Energy Density
Advisor: Christian Ochsenfeld

Research Interests

DFT Development:
I am mainly developing new density functional approximations (DFAs) beyond the w-B97M-V level which provide more accurate and more numerically stable descriptions of molecules and molecular properties without significantly raising the computational complexity (time and memory) of the method.
Scope of Application:
Due to their modest computational cost, these are particularly useful for the description of fragments (molecules, surfaces, bulk transitions, active sites of proteins etc.) within their respective physiochemical environments (e.g., explicit solvents, protein backbones) where typically hundreds of atoms need to be included in the quantum-mechanical (QM) description of the system.
Computational Efficiency:
In order to make such application even more affordable, I am also constantly refining the implementations of such hybrid-DFAs with a particular focus on modern, highly-parallel, high-performance-compute (HPC) platforms, e.g., parallel computing clusters and graphics processing units (GPUs). In particular, I leverage the technique of seminumerical integration to compute Fock-exchange-like interactions very efficiently within our sn-LinK framework.

Selected Publications

First Author

1. H. Laqua, J. C. B. Dietschreit, J. Kussmann, C. Ochsenfeld,
   “Accelerating Hybrid Density Functional Theory Molecular Dynamic Simulations by Seminumerical Integration, Resolution-of-the-Identity Approximation, and Graphics Processing Units”,
   J. Chem. Theory Comput., 18, 6010-6020 (2022).
2. H. Laqua, J. Kussmann, C. Ochsenfeld,
   “Accelerating seminumerical Fock-exchange calculations using mixed single- and double-precision arithmethic”,
   J. Chem. Phys., 154, 214116 (2021).
3. J. Kussmann, H. Laqua, C. Ochsenfeld,
   “Highly Efficient Resolution-of-Identity Density Functional Theory Calculations on Central and Graphics Processing Units”,
   J. Chem. Theory Comput., 17, 1512-1521 (2021).
4. H. Laqua, T. H. Thompson, J. Kussmann, C. Ochsenfeld,
   “Highly efficient, linear scaling seminumerical exact-exchange method for graphic processing units”,
   J. Chem. Theory Comput., 16, 1456-1468 (2020).
5. H. Laqua, J. Kussmann, C. Ochsenfeld,
   “An improved molecular partitioning scheme for numerical quadratures in density functional theory”,
   J. Chem. Phys., 149, 204111 (2018).
6. H. Laqua, J. Kussmann, C. Ochsenfeld,
   “Density functional theory model for multi-reference systems based on the exact-exchange hole normalization”,
   J. Chem. Phys. (Communication), 148, 121101 (2018) [Editor’s Pick and Editor’s Choice 2018].

Contributing Author

1. V. Drontschenko, D. Graf, H. Laqua, C. Ochsenfeld,
   “Efficient Method for the Computation of Frozen-Core Nuclear Gradients within the Random Phase Approximation”,
   J. Chem. Theory Comput., in press (2022).
2. F. Sacchetta, D. Graf, H. Laqua, M. Ambroise, J. Kussmann, A. Dreuw, C. Ochsenfeld,
   “An effective sub-quadratic scaling atomic-orbital reformulation of the scaled opposite-spin RI-CC2 ground-state model using Cholesky-decomposed densities and an attenuated Coulomb-metric”,
   J. Chem. Phys., 157, 104104 (2022).
3. V. Drontschenko, D. Graf, H. Laqua, C. Ochsenfeld,
   “A Lagrangian-Based Minimal-Overhead Batching Scheme for the Efficient Integral-Direct Evaluation of the RPA Correlation Energy”,
   J. Chem. Theory Comput., 17, 5623–5634 (2021).
4. A. Kreppel, D. Graf, H. Laqua, C. Ochsenfeld,
   “Range-Separated Density-Functional Theory in Combination with the Random Phase Approximation: An Accuracy Benchmark”,
   J. Chem. Theory Comput., 16, 2985-2994 (2020).