Re: [ESPResSo-users] FENE+LJ bond

Actually, they did not specify in the paper for which pairs of particles they used the usual LJ potential (Eq.1). They only say that the fene + LJ (WCA) with cut=2^1/6 sigma) is used for polymer-polymer interactions. The text suggests that they used Eq.1 for all particle pairs including the polymer but that would be a very wierd setting.

If you need to model exactly the same system, then I think that you should ask the authors for clarification. Otherwise, I would use WCA potential for polymer-polymer and LJ with cut=2.5sigma fro all other pairs.

Greetings,

peter

On Tue, May 21, 2019 at 2:54 PM Dusan Racko <address@hidden> wrote:

Hi, isn't that a cutoff for the attractive potential to model magnetic particles only? Sorry, I don't know the papers, just suggesting

On Tue, May 21, 2019 at 2:51 PM address@hidden <address@hidden> wrote:

Dear Peter,

Actually, in the paper, the cutoff distance of LJ potential between nonbonded beads is 2.5[sigma] while the cutoff distance of LJ potential between bonded beads is 2^(1/6)[sigma]. This can't be done by your way.
Thanks anyway!

Regards!
Ricky

address@hidden

From: Peter Košovan
Date: 2019-05-21 20:44
To: address@hidden
CC: address@hidden
Subject: Re: [ESPResSo-users] FENE+LJ bond
Hi Ricky,

Just set up a FENE potential between the given pair of particles, and an LJ potential between the given particle types (probably the same type) and you get exactly what you want. This is the standard setup which is just described in a weird way in the paper that you cited.

The fene potential acts just between the two particles with a given id. The LJ potential acts between any pair of particles. If your pair of particles interacts both with fene and LJ, then you get the fene+LJ interaction.

See also the script minimal-polymer.py in the samples directory.

peter

On Tue, May 21, 2019 at 10:37 AM address@hidden <address@hidden> wrote:

Dear Sebastian,

Thanks for your reply at first!
I want to model the hard-soft block copolymers with magnetic particles and the copolymer model I use is from this paper
https://link.aps.org/pdf/10.1103/PhysRevE.88.022602

In this paper, the bond potential is FENE+LJ. Beyond that, I can also find paper using FENE+LJ potentials in https://aip.scitation.org/doi/10.1063/1.458541. What's more, in LAMMPS, it also uses the FENE+LJ type fene bond.

I will use the FENE+LJ bond with bonded beads and the LJ potential with nonbonded beads.

Regards!
Ricky

address@hidden

--
Dr. Peter Košovan

Department of Physical and Macromolecular Chemistry
Faculty of Science, Charles University in Prague, Czech Republic

Katedra fyzikální a makromolekulární chemie
Přírodovědecká fakulta Univerzity Karlovy v Praze

www.natur.cuni.cz/chemistry/fyzchem/
Tel. +420221951029
Fax +420224919752

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Polymer Institute of the Slovak Academy of Sciences
Dubravska cesta 3
845 41 Bratislava, Slovak Republic [‡]
tel: +421 2 3229 4321
RG: https://www.researchgate.net/profile/Dusan_Racko
Scholar: https://goo.gl/oRVrGV

From:	Peter Košovan
Subject:	Re: [ESPResSo-users] FENE+LJ bond
Date:	Tue, 21 May 2019 14:59:00 +0200