Particle insertion with known temperature

[Adnan_Dani]

Hello Sir,

I am writing a hybrid code of LAMMPS and Fortran for evaporation. I need to insert gas particle in a gas and the problem with create_atom is that the new created particle is at rest initially. This in return lower the temperture of my simulation geometery. I need to insert this particle so that it did not lower the temperture of my configuration or in other words i need to insert this particle with known temperture that corresponds to the temperture of insertion point evniornment.

One trick was to insert the particles and set/rescale the temperture to known values. I want to know is there any other method to do that?

Secondly, i want to ask about insertion of a particle in a liquid. I found it very hard to insert a particle back to liquiid which did not effect the change in temperture of liquid. As i try to insert some particles in into the liquid and it cuases increase in temperture.

Adnan

[akohlmey]

@Adnan_Dani

and the problem with create_atom is that the new created particle is at rest initially.

I am confused about this. The documentation for the create_atoms function of the LAMMPS Fortran module clearly allows to also set velocities as optional parameters: 1.3.1. The LIBLAMMPS Fortran Module — LAMMPS documentation

@Adnan_Dani

I need to insert this particle so that it did not lower the temperture of my configuration or in other words i need to insert this particle with known temperture that corresponds to the temperture of insertion point evniornment.

There is no such thing a temperature for a single atom. Even the definition of temperature for a small group of atoms is dependent on assuming equipartitioning and fully ergodic behavior of the system under evaluation.

@Adnan_Dani

I want to know is there any other method to do that?

You could choose velocities according to a suitable distribution, similar to what the velocity input command does for a given target temperature and based on picking a random item from that distribution.

@Adnan_Dani

Secondly, i want to ask about insertion of a particle in a liquid. I found it very hard to insert a particle back to liquiid which did not effect the change in temperture of liquid. As i try to insert some particles in into the liquid and it cuases increase in temperture.

This is a topic for a discussion with your adviser or tutor. This the physics of the problem.