Method for making 2-electron response reduced density matrices approximately N-representable
| العنوان: | Method for making 2-electron response reduced density matrices approximately N-representable |
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| المؤلفون: | Klaas Gunst, Patrick Bultinck, Paul W. Ayers, Dimitri Van Neck, Stijn De Baerdemacker, Caitlin Lanssens |
| المصدر: | JOURNAL OF CHEMICAL PHYSICS |
| سنة النشر: | 2018 |
| مصطلحات موضوعية: | Normalization (statistics), Matrix norm, General Physics and Astronomy, FOS: Physical sciences, Positive-definite matrix, 01 natural sciences, Schrödinger equation, RENORMALIZATION-GROUP, ATOMS, symbols.namesake, MOLECULES, CONFIGURATION-INTERACTION, Physics - Chemical Physics, 0103 physical sciences, WAVE-FUNCTIONS, Applied mathematics, NONORTHOGONAL GEMINALS, Physical and Theoretical Chemistry, 010306 general physics, OPTIMIZATION, Eigenvalues and eigenvectors, Chemical Physics (physics.chem-ph), Quantum Physics, 010304 chemical physics, Geminal, QUANTUM-CHEMISTRY, ELECTRONS, Chemistry, Coupled cluster, Physics and Astronomy, Norm (mathematics), symbols, Quantum Physics (quant-ph), STRONGLY CORRELATED SYSTEMS |
| الوصف: | In methods like geminal-based approaches or coupled cluster that are solved using the projected Schr\"odinger equation, direct computation of the 2-electron reduced density matrix (2-RDM) is impractical and one falls back to a 2-RDM based on response theory. However, the 2-RDMs from response theory are not $N$-representable. That is, the response 2-RDM does not correspond to an actual physical $N$-electron wave function. We present a new algorithm for making these non-$N$-representable 2-RDMs approximately $N$-representable, i.e. it has the right symmetry and normalization and it fulfills the $P$-, $Q$- and $G$-conditions. Next to an algorithm which can be applied to any 2-RDM, we have also developed a 2-RDM optimization procedure specifically for seniority-zero 2-RDMs. We aim to find the 2-RDM with the right properties that is the closest (in the sense of the Frobenius norm) to the non-N-representable 2-RDM by minimizing the square norm of the difference between the initial 2-RDM and the targeted 2-RDM under the constraint that the trace is normalized and the 2-RDM, $Q$- and $G$-matrices are positive semidefinite, i.e. their eigenvalues are non-negative. Our method is suitable for fixing non-N-respresentable 2-RDMs which are close to being N-representable. Through the N-representability optimization algorithm we add a small correction to the initial 2-RDM such that it fulfills the most important N-representability conditions. Comment: 13 pages, 8 figures |
| وصف الملف: | application/pdf |
| تدمد: | 1089-7690 0021-9606 |
| URL الوصول: | https://explore.openaire.eu/search/publication?articleId=doi_dedup___::5069dc76886dc0026de27511875abcfc https://pubmed.ncbi.nlm.nih.gov/29495792 |
| حقوق: | OPEN |
| رقم الأكسشن: | edsair.doi.dedup.....5069dc76886dc0026de27511875abcfc |
| قاعدة البيانات: | OpenAIRE |
Find this article in full text from Scitation. | تدمد: | 10897690 00219606 |
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