Domains and defects in nuclear pasta

Journal Article · 06 November 2018 · Physical Review C

DOI: https://doi.org/10.1103/physrevc.98.055801 · OSTI ID:1565771

Schneider, A. S. ^[1]; Caplan, M. E. ^[2]; Berry, D. K. ^[3]; Horowitz, C. J. ^[3]

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1. California Inst. of Technology (CalTech), Pasadena, CA (United States)
2. McGill Univ., Montreal, QC (Canada)
3. Indiana Univ., Bloomington, IN (United States)

Nuclear pasta topology is an essential ingredient to determine transport properties in the inner crust of neutron stars. Herein we perform semiclassical molecular dynamics simulations of nuclear pasta for proton fractions $Y_p=0.30$ and $Y_p=0.40$ near one-third of nuclear saturation density, $n=0.05{\mathrm{fm}}^{–3}$, at a temperature $T=1.0\mathrm{MeV}$. Our simulations are, to our knowledge, the largest nuclear pasta simulations to date and contain up to $3276800$ nucleons in the $Y_p=0.30$ and $819200$ nucleons in the $Y_p=0.40$ case. An algorithm to determine which nucleons are part of a given sub-domain in the system is presented. By comparing runs of different sizes we study finite-size effects, equilibration time, the formation of multiple domains and defects in the pasta structures, as well as the structure factor dependence on simulation size. Although we find qualitative agreement between the topological structure and the structure factors of runs with 51 200 nucleons and those with $819200$ nucleons or more, we show that simulations with hundreds of thousands of nucleons may be necessary to accurately predict pasta transport properties.

• Research Organization: Indiana Univ., Bloomington, IN (United States); Michigan State Univ., East Lansing, MI (United States); Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
• Sponsoring Organization: Brazilian National Council for Scientific and Technological Development (CNPq); National Science Foundation (NSF); Natural Sciences and Engineering Research Council (NSERC) (Canada); USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR) (SC-21)
• Grant/Contract Number: AC05-00OR22725; FG02-87ER40365; SC0018083
• OSTI ID: 1565771
• Report Number(s): arXiv:1807.00102v1
• Journal Information: Physical Review C, Journal Name: Physical Review C Journal Issue: 5 Vol. 98; ISSN PRVCAN; ISSN 2469-9985
• Publisher: American Physical Society (APS)Copyright Statement
• Country of Publication: United States
• Language: English