Symmetry plays a crucial part in our understanding of the natural world. Mirror symmetry breaking is of special interest as it is related to life as we know it. Studying systems which display chiral amplification, therefore, could further our understanding of symmetry breaking in chemical systems, in general, and thus also of the asymmetry in Nature. Here, we report on strong chiral amplification in the colloidal synthesis of intrinsically chiral lanthanide phosphate nanocrystals, measured via circularly polarized luminescence. The amplification involves spontaneous symmetry breaking into either left- or right-handed nanocrystals below a critical temperature. Furthermore, chiral tartaric acid molecules in the solution direct the amplified nanocrystal handedness through a discontinuous transition between left- and right-handed excess. We analyze the observations based on the statistical thermodynamics of critical phenomena. Our results demonstrate how chiral minerals with high enantiopurity can form in a racemic aqueous environment.
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http://dx.doi.org/10.1073/pnas.1821923116 | DOI Listing |
J Chem Phys
January 2025
Lehrstuhl für Theoretische Chemie, Universität Erlangen-Nürnberg, Egerlandstr. 3, D-91058 Erlangen, Germany.
Methods based on density-functional theory usually treat open-shell atoms and molecules within the spin-unrestricted Kohn-Sham (KS) formalism, which breaks symmetries in real and spin space. Symmetry breaking is possible because the KS Hamiltonian operator does not need to exhibit the full symmetry of the physical Hamiltonian operator, but only the symmetry of the spin density, which is generally lower. Symmetry breaking leads to spin contamination and prevents a proper classification of the KS wave function with respect to the symmetries of the physical electron system.
View Article and Find Full Text PDFJ Chem Theory Comput
January 2025
Department of Chemistry, Rice University, Houston, Texas 77005-1892, United States.
Generalized Hartree-Fock (GHF) is a long-established electronic structure method that can lower the energy (compared to spin-restricted variants) by breaking physical wave function symmetries, namely and . After an exposition of GHF theory, we assess the use of GHF trial wave functions in phaseless auxiliary field quantum Monte Carlo (ph-AFQMC-G) calculations of strongly correlated molecular systems including symmetrically stretched hydrogen rings, carbon dioxide, and dioxygen. Imaginary time propagation is able to restore symmetry and yields energies of comparable or better accuracy than CCSD(T) with unrestricted HF and GHF references, and consistently smooth dissociation curves─a remarkable result given the relative scalability of ph-AFQMC-G to larger system sizes.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
School of Physics and Electronics, Hunan University, Changsha 410082, China.
Two-dimensional (2D) Janus structures with the breaking of out-of-plane mirror symmetry can induce many interesting physical phenomena, and have attracted widespread attention. Herein, we propose a MoPS monolayer with mirror asymmetry, identified by first-principles structural search calculations, which demonstrates high thermodynamic and dynamic stability. Our findings reveal that Mo 4d-orbitals dominate the metallicity, significantly enhancing the density of states near the Fermi level due to Van Hove singularities (VHSs), leading to the existence of phonon-mediated superconductivity.
View Article and Find Full Text PDFPhys Chem Chem Phys
January 2025
Department of Physics, Zhejiang Sci-Tech University, Hangzhou, Zhejiang 310018, People's Republic of China.
Two-dimensional (2D) carbon allotropes, together with their binary and ternary counterparts, have attracted substantial research interest due to their peculiar geometries and properties. Among them, grapheneplus, a derivative of penta-graphene, has been proposed to exhibit unusual mechanical and electronic behaviour. In this work, we perform a comprehensive first-principles study on its isoelectronic and isostructural analogue, a grapheneplus-like BCN (gp-BCN) monolayer.
View Article and Find Full Text PDFThe emission of N lasing at 391 nm from 800 nm femtosecond laser filament in air at 1 atm presents significant challenges due to the quenching effect induced by oxygen molecules. We introduce a simple technique for the 391 nm N lasing emission induced by a corona electric field-assisted femtosecond filament in air. This technique greatly addresses the challenge of exciting a 391 nm lasing from 800 nm femtosecond laser filament in air at 1 atm.
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