Self-diffusion anomalies of an odd tracer in soft-core media
Odd-diffusive systems, characterised by broken time-reversal and/or parity, have recently been shown to display counterintuitive features such as interaction-enhanced dynamics in the dilute limit. Here we extend the investigation to the high-density limit of an odd tracer embedded in a soft medium d...
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IOP Publishing
2025-01-01
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| Series: | New Journal of Physics |
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| Online Access: | https://doi.org/10.1088/1367-2630/adbdea |
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| author | Pietro Luigi Muzzeddu Erik Kalz Andrea Gambassi Abhinav Sharma Ralf Metzler |
| author_facet | Pietro Luigi Muzzeddu Erik Kalz Andrea Gambassi Abhinav Sharma Ralf Metzler |
| author_sort | Pietro Luigi Muzzeddu |
| collection | DOAJ |
| description | Odd-diffusive systems, characterised by broken time-reversal and/or parity, have recently been shown to display counterintuitive features such as interaction-enhanced dynamics in the dilute limit. Here we extend the investigation to the high-density limit of an odd tracer embedded in a soft medium described by the Gaussian core model (GCM) using a field-theoretic approach based on the Dean–Kawasaki equation. Our analysis reveals that interactions can enhance the dynamics of an odd tracer even in dense systems. We demonstrate that oddness results in a complete reversal of the well-known self-diffusion ( $D_\mathrm{s}$ ) anomaly of the GCM. Ordinarily, $D_\mathrm{s}$ exhibits a non-monotonic trend with increasing density, approaching but remaining below the interaction-free diffusion, D _0 , ( $D_\mathrm{s} \lt D_0$ ) so that $D_\mathrm{s} \uparrow D_0$ at high densities. In contrast, for an odd tracer, self-diffusion is enhanced ( $D_\mathrm{s} \gt D_0$ ) and the GCM anomaly is inverted, displaying $D_\mathrm{s} \downarrow D_0$ at high densities. The transition between the standard and reversed GCM anomaly is governed by the tracer’s oddness, with a critical oddness value at which the tracer diffuses as a free particle ( $D_\mathrm{s} \approx D_0$ ) across all densities. We validate our theoretical predictions with Brownian dynamics simulations, finding strong agreement between the them. |
| format | Article |
| id | doaj-art-17fbfc445a114e54891e82a11cede65f |
| institution | OA Journals |
| issn | 1367-2630 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | IOP Publishing |
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| series | New Journal of Physics |
| spelling | doaj-art-17fbfc445a114e54891e82a11cede65f2025-08-20T02:10:42ZengIOP PublishingNew Journal of Physics1367-26302025-01-0127303302510.1088/1367-2630/adbdeaSelf-diffusion anomalies of an odd tracer in soft-core mediaPietro Luigi Muzzeddu0https://orcid.org/0000-0002-1059-8240Erik Kalz1https://orcid.org/0000-0003-3294-7365Andrea Gambassi2https://orcid.org/0000-0003-3450-6125Abhinav Sharma3https://orcid.org/0000-0002-6436-3826Ralf Metzler4https://orcid.org/0000-0002-6013-7020Department of Biochemistry, University of Geneva , CH-1211 Geneva, SwitzerlandUniversity of Potsdam, Institute of Physics and Astronomy , D-14476 Potsdam, GermanySISSA—International School for Advanced Studies , IT-34136 Trieste, Italy; INFN—Sezione di Trieste , IT-34127 Trieste, ItalyUniversity of Augsburg , Institute of Physics, D-86159 Augsburg, Germany; Leibniz-Institute for Polymer Research, Institute Theory of Polymers , D-01069 Dresden, GermanyUniversity of Potsdam, Institute of Physics and Astronomy , D-14476 Potsdam, Germany; Asia Pacific Centre for Theoretical Physics , KR-37673 Pohang, Republic of KoreaOdd-diffusive systems, characterised by broken time-reversal and/or parity, have recently been shown to display counterintuitive features such as interaction-enhanced dynamics in the dilute limit. Here we extend the investigation to the high-density limit of an odd tracer embedded in a soft medium described by the Gaussian core model (GCM) using a field-theoretic approach based on the Dean–Kawasaki equation. Our analysis reveals that interactions can enhance the dynamics of an odd tracer even in dense systems. We demonstrate that oddness results in a complete reversal of the well-known self-diffusion ( $D_\mathrm{s}$ ) anomaly of the GCM. Ordinarily, $D_\mathrm{s}$ exhibits a non-monotonic trend with increasing density, approaching but remaining below the interaction-free diffusion, D _0 , ( $D_\mathrm{s} \lt D_0$ ) so that $D_\mathrm{s} \uparrow D_0$ at high densities. In contrast, for an odd tracer, self-diffusion is enhanced ( $D_\mathrm{s} \gt D_0$ ) and the GCM anomaly is inverted, displaying $D_\mathrm{s} \downarrow D_0$ at high densities. The transition between the standard and reversed GCM anomaly is governed by the tracer’s oddness, with a critical oddness value at which the tracer diffuses as a free particle ( $D_\mathrm{s} \approx D_0$ ) across all densities. We validate our theoretical predictions with Brownian dynamics simulations, finding strong agreement between the them.https://doi.org/10.1088/1367-2630/adbdeainteracting colloidsodd diffusionDean–Kawasaki equationstochastic field theoryself-diffusion anomalyGaussian core model |
| spellingShingle | Pietro Luigi Muzzeddu Erik Kalz Andrea Gambassi Abhinav Sharma Ralf Metzler Self-diffusion anomalies of an odd tracer in soft-core media New Journal of Physics interacting colloids odd diffusion Dean–Kawasaki equation stochastic field theory self-diffusion anomaly Gaussian core model |
| title | Self-diffusion anomalies of an odd tracer in soft-core media |
| title_full | Self-diffusion anomalies of an odd tracer in soft-core media |
| title_fullStr | Self-diffusion anomalies of an odd tracer in soft-core media |
| title_full_unstemmed | Self-diffusion anomalies of an odd tracer in soft-core media |
| title_short | Self-diffusion anomalies of an odd tracer in soft-core media |
| title_sort | self diffusion anomalies of an odd tracer in soft core media |
| topic | interacting colloids odd diffusion Dean–Kawasaki equation stochastic field theory self-diffusion anomaly Gaussian core model |
| url | https://doi.org/10.1088/1367-2630/adbdea |
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