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Re: [lammps-users] Question on pair_style dpd
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Re: [lammps-users] Question on pair_style dpd


From: Axel Kohlmeyer <akohlmey@...24...>
Date: Fri, 25 May 2018 18:43:44 -0400



On Thu, May 24, 2018 at 1:15 AM, Boyuan Yu <BoyuanYU0715@...33....4215...> wrote:

Hi all,

 

I try to use LAMMPS pair_style dpd to reproduce the morphologies of diblock block copolymer melt obtained in Groot’s paper (Dynamic simulation of diblock copolymer microphase separation). However, with the parameters supposed to get lamellae phase, I got a disordered phase while in HOOMD-blue, I could get lamellae phase. I have attached my input files and result below. I wonder if there is anything wrong with my input scripts or if there is any issue with the dpd pair_style in LAMMPS.


​nobody here will do the debugging of your inputs for you.​ if you feel, that LAMMPS is not computing interactions correctly, the burden of proof is on you and not vice versa it is not our job to point out where you are doing something different than from what you do with HOOMD.
 

Particularly, I want to know when LAMMPS calculates non-bonded interactions, by default, will it exclude bonded atoms or not?


​if you do not change the speacial_bonds settings, all 1-2, 1-3, and 1-4 pairs (it doesn't matter whether you have no angles or dihedrals) are excluded from the neighbor list and thus from contributing to non-bonded​ interactions.

axel.

 

 

 

Thanks,

Boyuan

 

Part of the polymer.txt file

# Diblock copolymer melt

 

24000 atoms

2 atom types

21600 bonds

1 bond types

 

0 20 xlo xhi

0 20 ylo yhi

0 20 zlo zhi

 

Atoms # bond

 

1      1      1      19.2237  8.52157  8.00038

2      1      1      19.1454  8.76061  8.41504

3      1      1      19.7577  9.10032  7.70855

4      1      1      19.8181  9.05956  7.32281

5      1      1      19.6175  9.47839  7.35945

6      1      2      19.5462  9.33713  7.40166

7      1      2      19.24      9.24531  7.68145

8      1      2      19.082    9.01368  7.59658

9      1      2      19.3272  8.73811  7.32866

10    1      2      19.7041  8.63656  7.61278

11    2      1      15.7688  16.0142  12.4761

12    2      1      15.8157  16.2 12.5508

13    2      1      15.8752  15.4791  12.9142

14    2      1      16.0583  15.3646  12.8215

15    2      1      15.7808  15.1941  12.9312

16    2      2      15.5727  15.0802  12.3917

17    2      2      15.962    15.1947  12.5356

18    2      2      15.5992  15.357    12.396

19    2      2      15.0698  15.2993  12.0094

20    2      2      14.7752  14.9839  11.9955

.

.

.

Bonds

 

1      1      1      2

2      1      2      3

3      1      3      4

4      1      4      5

5      1      5      6

6      1      6      7

7      1      7      8

8      1      8      9

9      1      9      10

10    1      11    12

11    1      12    13

12    1      13    14

13    1      14    15

14    1      15    16

15    1      16    17

16    1      17    18

17    1      18    19

18    1      19    20

19    1      21    22

20    1      22    23

.

.

.

 


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--
Dr. Axel Kohlmeyer  akohlmey@...12...24...  http://goo.gl/1wk0
College of Science & Technology, Temple University, Philadelphia PA, USA
International Centre for Theoretical Physics, Trieste. Italy.