Category Archives: MM/MD @en

LAMMPS

Biochemistry, MM/MD @en, Software_en

LAMMPS (“Large-scale Atomic/Molecular Massively Parallel Simulator”) is a molecular dynamics program from Sandia National Laboratories. LAMMPS makes use of MPI for parallel communication and is a free open-source code, distributed under the terms of the GNU General Public License.
LAMMPS was originally developed under a Cooperative Research and Development Agreement (CRADA) between two laboratories from United States Department of Energy and three other laboratories from private sector firms. It is currently maintained and distributed by researchers at the Sandia National Laboratories. (Taken from Wikipedia). Jun-05-2019 version.

General Information

LAMMPS is a classical molecular dynamics code that models an ensemble of particles in a liquid, solid, or gaseous state. It can model atomic, polymeric, biological, metallic, granular, and coarse-grained systems using a variety of force fields and boundary conditions.

In the most general sense, LAMMPS integrates Newton’s equations of motion for collections of atoms, molecules, or macroscopic particles that interact via short- or long-range forces with a variety of initial and/or boundary conditions. For computational efficiency LAMMPS uses neighbor lists to keep track of nearby particles. The lists are optimized for systems with particles that are repulsive at short distances, so that the local density of particles never becomes too large. On parallel machines, LAMMPS uses spatial-decomposition techniques to partition the simulation domain into small 3d sub-domains, one of which is assigned to each processor. Processors communicate and store “ghost” atom information for atoms that border their sub-domain. LAMMPS is most efficient (in a parallel sense) for systems whose particles fill a 3d rectangular box with roughly uniform density. Papers with technical details of the algorithms used in LAMMPS are listed in this section.

How to Use

send_lmp

  • To send LAMMPS to the queue system  use the send_lmp utility. When executed,
    shows the command syntax, which is summarized below:
  • send_lmp JOBNAME NODES PROCS_PER_NODE TIME [ MEM ] [``Other queue options'' ]
    JOBNAME: Is the  name of the input with extension.
    NODES: Number of nodes.
    PROCS: Number of  processors.
    TIME: Time requested to the queue system, format hh:mm:ss.
    MEM: Optional. Memory in Gb ( It will used 1GB/core if not set).
    [``Other Torque Options'' ] Optional. There is the possibility to pass more variables to the queuing system.
    See examples below.   More information about this options

Examples

We send the lammps input job1 to 1 node, 4 processors on that node, with a requested time of 4 hours:

send_lmp job1.in 1 4 04:00:00

We send job2  to 2 compuation nodes, 8 processors on each node, with a requested time of 192 hours, 8 GB of RAM and to start running after work 1234.arinab is finished:

send_lmp job2.inp 2 8 192:00:00 8 ``-W depend=afterany:1234'

We  send the input job3 to 4 nodes and 4 processors on each node, with arequested time of 200:00:00 hours, 2 GB of RAM and we request to be send an email at the beginning and end of the calculation to the direction specified.

send_lmp job.tpr 4 4 200:00:00 2 ``-m be -M mi.email@ehu.es''

send_lmp command copies the contents of the directory from which the job is sent to /scratch or / gscratch, if we use 2 or more nodes. And there is where the calculation is done.

Jobs Monitoring

To facilitate monitoring and/or control of the LAMMPS calculations, you can use remote_vi

remote_vi JOBID

It show us the *.out file  (only if it was sent using send_lmp).

More information

http://lammps.sandia.gov

GROMACS

Biochemistry, MM/MD @en, Scientific Software

General information

2018 version. GROMACS is a versatile package to perform molecular dynamics, i.e. simulate the Newtonian equations of motion for systems with hundreds to millions of particles.

It is primarily designed for biochemical molecules like proteins, lipids and nucleic acids that have a lot of complicated bonded interactions, but since GROMACS is extremely fast at calculating the nonbonded interactions (that usually dominate simulations) many groups are also using it for research on non-biological systems, e.g. polymers.

How to use

send_gmx

To send gromacs to the queue system  use the send_gmx utility. When executed, shows the command syntax, which is summarized below:

send_gmx ``JOB and Options'' NODES PROCS_PER_NODE TIME MEM [``Other queue options'']
``JOB and Options'': options for the calculation and input of GROMACS name extension. It is very important to keep the quotes.
NODES: Number of nodes.
PROCS: Number of  processors.
TIME: Time requested to the queue system, format hh:mm:ss.
MEM: Memory in Gb.
[``Otras opciones de Torque'' ] There is the possibility to pass more variables to the queuing system.
See examples below.  [intlink id=”244″ type=”post”] More information about this options[/intlink]

Examples

We send the gromacs input job1 to 1 node, 4 processors on that node, with a requested time of 4 hours and 1 GB of RAM:

send_gmx ``-s job1.tpr'' 1 4 04:00:00 1

We send job2  to 2 compuation nodes, 8 processors on each node, with a requested time of 192 hours, 8 GB of RAM and to start running after work 1234.arinab is finished:

send_gmx ``-s job2.tpr'' 2 8 192:00:00 8 ``-W depend=afterany:1234'

We  send the input job3 to 4 nodes and 4 processors on each node, with a requested time of 200:00:00 hours, 2 GB of RAM and we request to be send an email at the  beginning and end of the calculation to the direction specified.

send_gmx ``-s  job.tpr'' 4 4 200:00:00 2 ``-m be -M mi.email@ehu.es''

send_gmx command copies the contents of the directory from which the job is sent to /scratch or /gscratch, if we use 2 or more nodes. And there is where the calculation is done.

Jobs Monitoring

To facilitate monitoring and/or control of the gromacs calculations, you can use remote_vi which shows the md.log file (only if it was sent using send_gmx).

More information

http://www.gromacs.org/About_Gromacs