Title :

Assessing MP2 frozen natural orbitals for relativistic electronic structure

Author(s) :

Yuan, Xiang [Orateur]
Physico-Chimie Moléculaire Théorique [PCMT]
Visscher, Lucas [Auteur]
Severo Pereira Gomes, Andre [Auteur]
Physico-Chimie Moléculaire Théorique [PCMT]

Conference title :

Workshop of the GDR quantum gases

City :

Lille

Country :

France

Start date of the conference :

2022-10-24

Publication date :

2022-10-24

HAL domain(s) :

Chimie/Chimie théorique et/ou physique
Physique [physics]/Physique [physics]/Chimie-Physique [physics.chem-ph]

English abstract : [en]

The O(N⁶) computation cost is a bottleneck preventing performing Coupled-Cluster (CC) on large systems, particularly when employing 4- component based relativistic Hamiltonians, for which in practice one often ...
Show more >The O(N⁶) computation cost is a bottleneck preventing performing Coupled-Cluster (CC) on large systems, particularly when employing 4- component based relativistic Hamiltonians, for which in practice one often uses uncontracted basis set generating large virtual molecular orbitalspaces.<br>The canonical Hartree-Fock (HF) orbitals are not the most compact representation for post HF method. On other hand, using natural orbital is an efficient way to reduce the orbital space and maintains most of the accuracy. We therefore implemented the MP2 frozen natural orbital (FNO) method [1] in the Exacorr code [2], with the particularity that our implementation can generate both complex and quaternion FNOs, and also express these in AO basis. It also allows us to obtain CCSD natural orbitals on AO basis, which can be subsequently used in analysis. We have investigated the orbital truncation errors in both correlation energy and molecular properties including dipole, quadrupole moment, electric filed gradient, for hydrogen halides HX (X=F, Cl, Br, I, At, Ts), and parity violation for the H₂X₂ (X= O, S, Se, Te, Po) molecules. We find that FNO indeed accelerates rapidly the correlation energy convergence. For properties, truncated FNO spaces seem to slightly outperform canonical HF orbitals, and to provide reliable estimates for the molecular properties obtained for complete virtual spaces [3].<b>Reference</b>[1] T. L. Barr, E. R. Davidson, Phys. Rev. A 1970, 1, 644; A. G. Taube, R. J. Bartlett, <i>J. Chem. Phys.</i> 2008, <b>128</b>, 164101<br>[2] J. V. Pototschnig, A. Papadopoulos, D. I. Lyakh, M. Repisky, L. Halbert, A. S. P. Gomes, H- JAa. Jensen, L. Visscher, <i>J. Chem. Theory. Comput.</i> 2021, <b>17</b>, 5509<br>[3] X. Yuan, L. Visscher, ASP. Gomes, <i>J. Chem. Phys.</i> 2022, arXiv:2202.01146<br>Show less >

Language :

Anglais

Peer reviewed article :

Oui

Audience :

Nationale

Popular science :

Non

ANR Project :

Physiques et Chimie de l'Environnement Atmosphérique
ULNE
Calcul de la diffusion inélastique résonante de rayons X pour toute la classification périodique

Collections :

• Laboratoire de Physique des Lasers, Atomes et Molécules (PhLAM) - UMR 8523

Source :

Harvested from HAL

Submission date :

2023-05-07T20:47:42Z