Question on pair_style dpd

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

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

.

.

.

lammps.bmp (687 KB)

polymer.in (743 Bytes)

polymer.out (2.1 KB)

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.