9.3. Run path-integral MD with i-PI
The i-PI works in a client-server model. The i-PI provides the server for integrating the replica positions of atoms, while the DeePMD-kit provides a client named dp_ipi
that computes the interactions (including energy, forces and virials). The server and client communicate via the Unix domain socket or the Internet socket. Installation instructions for i-PI can be found here. The client can be started by
i-pi input.xml &
dp_ipi water.json
It is noted that multiple instances of the client allow for computing, in parallel, the interactions of multiple replicas of the path-integral MD.
water.json
is the parameter file for the client dp_ipi
, and an example is provided:
{
"verbose": false,
"use_unix": true,
"port": 31415,
"host": "localhost",
"graph_file": "graph.pb",
"coord_file": "conf.xyz",
"atom_type": {
"OW": 0,
"HW1": 1,
"HW2": 1
}
}
The option use_unix
is set to true
to activate the Unix domain socket, otherwise, the Internet socket is used.
The option port
should be the same as that in input.xml:
<port>31415</port>
The option graph_file
provides the file name of the frozen model. The model can have either double or single float precision interface.
The dp_ipi
gets the atom names from an XYZ file provided by coord_file
(meanwhile ignores all coordinates in it) and translates the names to atom types by rules provided by atom_type
.