arXiv - PHYS - Atomic and Molecular Clusters最新文献_第4页

Many-body theory calculations of positronic-bonded molecular dianions 正电子键合分子离子的多体理论计算

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-11-23 DOI: arxiv-2311.16318

J. P. Cassidy, J. Hofierka, B. Cunningham, D. G. Green

{"title":"Many-body theory calculations of positronic-bonded molecular dianions","authors":"J. P. Cassidy, J. Hofierka, B. Cunningham, D. G. Green","doi":"arxiv-2311.16318","DOIUrl":"https://doi.org/arxiv-2311.16318","url":null,"abstract":"The energetic stability of positron di-anion systems [A$^-;e^+;$A$^-$] is\u0000studied via many-body theory, where $A^-$ includes H$^{-}$, F$^{-}$, Cl$^{-}$\u0000and the molecular anions (CN)$^{-}$ and (NCO)$^{-}$. Specifically, the energy\u0000of the system as a function of ionic separation is determined by solving the\u0000Dyson equation for the positron in the field of the two anions, using a\u0000positron-anion self energy as constructed in [J. Hofierka, B. Cunningham, C. M.\u0000Rawlins, C. H. Patterson and D. G. Green, emph{Nature} {bf 606} 688 (2022)]\u0000that accounts for correlations including polarization, screening, and\u0000virtual-positronium formation. Calculations are performed for a positron\u0000interacting with H$_{2}^{2-}$, F$_{2}^{2-}$, and Cl$_{2}^{2-}$, and are found\u0000to be in good agreement with previous theory. In particular, we confirm the\u0000presence of two minima in the potential energy of the [H$^-;e^+$;H$^-$] system\u0000with respect to ionic separation: one a positronically-bonded [H$^-;e^+$;H$^-$]\u0000local minimum at ionic separations $rsim3.4$~AAphantom{}, and a global\u0000minimum at smaller ionic separations $rlesssim1.6$~AAphantom{} that gives\u0000overall instability of the system with respect to dissociation into a H$_2$\u0000molecule and a positronium negative ion, Ps$^-$. The first predictions are made\u0000for positronic bonding in dianions consisting of molecular anionic fragments,\u0000specifically for (CN)$_{2}^{2-}$, and (NCO)$_{2}^{2-}$. In all cases we find\u0000that the molecules formed by the creation of a positronic bond are stable\u0000relative to dissociation into A$^-$ and $e^+$A$^-$ (positron bound to a single\u0000anion), with bond energies on the order of 1~eV and bond lengths on the order\u0000of several r angstroms.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"6 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522716","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Automated detection of laser cooling schemes for ultracold molecules 超冷分子激光冷却方案的自动检测

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-11-14 DOI: arxiv-2311.08381

Anna Dawid, Niccolò Bigagli, Daniel W. Savin, Sebastian Will

{"title":"Automated detection of laser cooling schemes for ultracold molecules","authors":"Anna Dawid, Niccolò Bigagli, Daniel W. Savin, Sebastian Will","doi":"arxiv-2311.08381","DOIUrl":"https://doi.org/arxiv-2311.08381","url":null,"abstract":"One of the demanding frontiers in ultracold science is identifying laser\u0000cooling schemes for complex atoms and molecules, out of their vast spectra of\u0000internal states. Motivated by a need to expand the set of available ultracold\u0000molecules for applications in fundamental physics, chemistry, astrochemistry,\u0000and quantum simulation, we propose and demonstrate an automated graph-based\u0000search approach for viable laser cooling schemes. The method is time efficient\u0000and the outcomes greatly surpass the results of manual searches used so far. We\u0000discover new laser cooling schemes for C$_2$, OH$^+$, CN, YO, and CO$_2$ that\u0000can be viewed as surprising or counterintuitive compared to previously\u0000identified laser cooling schemes. In addition, a central insight of this work\u0000is that the reinterpretation of quantum states and transitions between them as\u0000a graph can dramatically enhance our ability to identify new quantum control\u0000schemes for complex quantum systems. As such, this approach will also be\u0000applicable to complex atoms and, in fact, any complex many-body quantum system\u0000with a discrete spectrum of internal states.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"15 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522724","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Time-Resolved Coulomb Explosion Imaging Unveils Ultrafast Ring Opening of Furan 时间分辨库仑爆炸成像揭示了呋喃的超快开环

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-11-09 DOI: arxiv-2311.05099

Enliang Wang, Surjendu Bhattacharyya, Keyu Chen, Kurtis Borne, Farzaneh Ziaee, Shashank Pathak, Huynh Van Sa Lam, Anbu Selvam Venkatachalam, Xiangjun Chen, Rebecca Boll, Till Jahnke, Artem Rudenko, Daniel Rolles

{"title":"Time-Resolved Coulomb Explosion Imaging Unveils Ultrafast Ring Opening of Furan","authors":"Enliang Wang, Surjendu Bhattacharyya, Keyu Chen, Kurtis Borne, Farzaneh Ziaee, Shashank Pathak, Huynh Van Sa Lam, Anbu Selvam Venkatachalam, Xiangjun Chen, Rebecca Boll, Till Jahnke, Artem Rudenko, Daniel Rolles","doi":"arxiv-2311.05099","DOIUrl":"https://doi.org/arxiv-2311.05099","url":null,"abstract":"Following the changes in molecular structure throughout the entirety of a\u0000chemical reaction with atomic resolution is a long-term goal in femtochemistry.\u0000Although the development of a plethora of ultrafast technique has enabled\u0000detailed investigations of the electronic and nuclear dynamics on femtosecond\u0000time scales, direct and unambiguous imaging of the nuclear motion during a\u0000reaction is still a major challenge. Here, we apply time-resolved Coulomb\u0000explosion imaging with femtosecond near-infrared pulses to visualize the\u0000ultraviolet-induced ultrafast molecular dynamics of gas-phase furan. Widely\u0000contradicting predictions and observations for this molecule have been reported\u0000in the literature. By combining the experimental Coulomb explosion imaging data\u0000with ab initio molecular dynamics and Coulomb explosion simulations, we reveal\u0000the presence of a strong ultrafast ring-opening pathway upon excitation at 198\u0000nm that occurs within 100 fs.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Absorption spectra of the purple nonsulfur bacteria light-harvesting complex: a DFT study of the B800 part 紫色非硫细菌捕光复合物的吸收光谱:B800部分的DFT研究

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-11-03 DOI: arxiv-2311.02024

L. V. Begunovich, E. A. Kovaleva, M. M. Korshunov, V. F. Shabanov

引用次数: 0

Coherent spin-phonon scattering in facilitated Rydberg lattices 易化里德堡晶格中的相干自旋声子散射

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-31 DOI: arxiv-2311.00064

Matteo Magoni, Chris Nill, Igor Lesanovsky

{"title":"Coherent spin-phonon scattering in facilitated Rydberg lattices","authors":"Matteo Magoni, Chris Nill, Igor Lesanovsky","doi":"arxiv-2311.00064","DOIUrl":"https://doi.org/arxiv-2311.00064","url":null,"abstract":"We investigate the dynamics of a spin system with facilitation constraint\u0000that can be studied using Rydberg atoms in arrays of optical tweezer traps. The\u0000elementary degrees of freedom of the system are domains of Rydberg excitations\u0000that expand ballistically through the lattice. Due to mechanical forces,\u0000Rydberg excited atoms are coupled to vibrations within their traps. At zero\u0000temperature and large trap depth, it is known that virtually excited lattice\u0000vibrations only renormalize the timescale of the ballistic propagation.\u0000However, when vibrational excitations are initially present -- i.e., when the\u0000external motion of the atoms is prepared in an excited Fock state, coherent\u0000state or thermal state -- resonant scattering between spin domain walls and\u0000phonons takes place. This coherent and deterministic process, which is free\u0000from disorder, leads to a reduction of the power-law exponent characterizing\u0000the expansion of spin domains. Furthermore, the spin domain dynamics is\u0000sensitive to the coherence properties of the atoms' vibrational state, such as\u0000the relative phase of coherently superimposed Fock states. Even for a\u0000translationally invariant initial state the latter manifests macroscopically in\u0000a phase-sensitive asymmetric expansion.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Systematic Improvement of Empirical Energy Functions in the Era of Machine Learning

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-28 DOI: arxiv-2310.18655

Mike Devereux, Eric D. Boittier, Makrus Meuwly

{"title":"Systematic Improvement of Empirical Energy Functions in the Era of Machine Learning","authors":"Mike Devereux, Eric D. Boittier, Makrus Meuwly","doi":"arxiv-2310.18655","DOIUrl":"https://doi.org/arxiv-2310.18655","url":null,"abstract":"The impact of targeted replacement of individual terms in empirical force\u0000fields is quantitatively assessed for pure water, dichloromethane (DCM), and\u0000solvated K$^+$ and Cl$^-$ ions. For the electrostatics, point charges (PCs) and\u0000machine learning (ML)based minimally distributed charges (MDCM) fitted to the\u0000molecular electrostatic potential are evaluated together with electrostatics\u0000based on the Coulomb integral. The impact of explicitly including second-order\u0000terms is investigated by adding a fragment molecular orbital (FMO)-derived\u0000polarization energy to an existing force field, in this case CHARMM. It is\u0000demonstrated that anisotropic electrostatics reduce the RMSE for water (by 1.6\u0000kcal/mol), DCM (by 0.8 kcal/mol) and for solvated Cl$^-$ clusters (by 0.4\u0000kcal/mol). An additional polarization term can be neglected for DCM but notably\u0000improves errors in pure water (by 1.1 kcal/mol) and in Cl$^-$ clusters (by 0.4\u0000kcal/mol) and is key to describing solvated K$^+$, reducing the RMSE by 2.3\u0000kcal/mol. A 12-6 Lennard-Jones functional form is found to perform\u0000satisfactorily with PC and MDCM electrostatics, but is not appropriate for\u0000descriptions that account for the electrostatic penetration energy. The\u0000importance of many-body contributions is assessed by comparing a strictly\u00002-body approach with self-consistent reference data. DCM can be approximated\u0000well with a 2-body potential while water and solvated K$^+$ and Cl$^-$ ions\u0000require explicit many-body corrections. The present work systematically\u0000quantifies which terms improve the performance of an existing force field and\u0000what reference data to use for parametrizing these terms in a tractable fashion\u0000for ML fitting of pure and heterogeneous systems.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"19 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522721","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Improved action for contact effective field theory 改进动作接触有效场理论

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-24 DOI: arxiv-2310.15760

Lorenzo Contessi, Martin Schäfer, Ubirajara van Kolck

引用次数: 0

Observation of interatomic Coulombic decay induced by double excitation of helium in nanodroplets 纳米液滴中氦双激发原子间库仑衰变的观察

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-24 DOI: arxiv-2310.15835

B. Bastian, J. D. Asmussen, L. Ben Ltaief, H. B. Pedersen, K. Sishodia, S. De, S. R. Krishnan, C. Medina, N. Pal, R. Richter, N. Sisourat, M. Mudrich

引用次数: 0

O(1) benchmarking of precise rotation in a spin-squeezed Bose-Einstein condensate 自旋压缩玻色-爱因斯坦凝聚体中精确旋转的0(1)基准

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-24 DOI: arxiv-2310.15473

Peng Du, Hui Tang, Jun Zhang, Wenxian Zhang

引用次数: 0

Direct evidence of helium rain in Jupiter and Saturn 木星和土星存在氦雨的直接证据

arXiv - PHYS - Atomic and Molecular Clusters Pub Date : 2023-10-20 DOI: arxiv-2310.13412

Xiaoju Chang, Bo Chen, Qiyu Zeng, Han Wang, Kaiguo Chen, Qunchao Tong, Xiaoxiang Yu, Dongdong Kang, Shen Zhang, Fangyu Guo, Yong Hou, Zengxiu Zhao, Yansun Yao, Yanming Ma, Jiayu Dai

{"title":"Direct evidence of helium rain in Jupiter and Saturn","authors":"Xiaoju Chang, Bo Chen, Qiyu Zeng, Han Wang, Kaiguo Chen, Qunchao Tong, Xiaoxiang Yu, Dongdong Kang, Shen Zhang, Fangyu Guo, Yong Hou, Zengxiu Zhao, Yansun Yao, Yanming Ma, Jiayu Dai","doi":"arxiv-2310.13412","DOIUrl":"https://doi.org/arxiv-2310.13412","url":null,"abstract":"The immiscibility of hydrogen-helium mixture under the temperature and\u0000pressure conditions of planetary interiors is crucial for understanding the\u0000structures of gas giant planets (e.g., Jupiter and Saturn). While the\u0000experimental probe at such extreme conditions is challenging, theoretical\u0000simulation is heavily relied in an effort to unravel the mixing behavior of\u0000hydrogen and helium. Here we develop a method via a machine learning\u0000accelerated molecular dynamics simulation to quantify the physical separation\u0000of hydrogen and helium under the conditions of planetary interiors. The\u0000immiscibility line achieved with the developed method yields substantially\u0000higher demixing temperatures at pressure above 1.5 Mbar than earlier\u0000theoretical data, but matches better to the experimental estimate. Our results\u0000revise the structures of Jupiter and Saturn where H-He demixing takes place in\u0000a large fraction of the interior radii, i.e., 27.5% in Jupiter and 48.3% in\u0000Saturn. This direct evidence of an H-He immiscible layer supports the formation\u0000of helium rain and explains the helium reduction in atmosphere of Jupiter and\u0000Saturn.","PeriodicalId":501259,"journal":{"name":"arXiv - PHYS - Atomic and Molecular Clusters","volume":"45 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138522613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0