CHAMP CLI

This document explains how to use the CHAMP program from the command line. It is based directly on the program’s source-code modules responsible for execution control, calculation modes (VMC/DMC), periodic settings, file handling, and command-line parsing.

Overview¶

CHAMP is controlled at runtime using both:

Command-line flags — specify input/output/error files, verbosity, debug mode, etc.
Input files (.in, .inp, .dat) — define calculation parameters for:
- VMC (vmc.inp)
- DMC (dmc.inp)

The program supports both serial and MPI-aware execution.

Basic Command Structure¶

The basic command line structure of CHAMP looks like:

/path/to/champ/bin/vmc.mov1 -i input.inp -o output.log -e error

Only the master MPI rank (rank 0) writes output; worker ranks redirect output to /dev/null for clean parallel runs.

A successfully built CHAMP provides two executables in the bin directory.

vmc.mov1 for VMC one-electron move
dmc.mov1 for DMC one-electron move

Command-Line Options¶

CHAMP recognizes several command-line flags, handled inside the contrl_file module.

Required / Most Common Flags¶

Flag(s)	Description
`-i`, `-in`, `-inp`, `-input`, `--input`	Specify input file (.in, .inp, *.dat)
`-o`, `-out`, `--output`	Output file (master rank only; workers redirect to /dev/null)
`-e`, `-err`, `--error`	Error and warnings log file

Optional Flags¶

Flag(s)	Description
`-v`, `--version`	Print version information and exit
`-h`, `--help`	Print help and exit
`-V`, `--verbose`	Enable verbose output
`-d`, `--debug`	Enable debug mode
`-p`, `--prefix`	Add prefix to generated files

Example: Get help¶

champ/bin/vmc.mov1 -h

Execution Modes¶

Execution mode is controlled by the control module. You can set mode inside input files or via initialization routines:

vmc — Variational Monte Carlo
dmc — Diffusion Monte Carlo

Verbosity (ipr) controls output level:

ipr value	Meaning
-1	minimal output
0	normal (default)
1	increasingly verbose, debug-level output
>2	All possible print output

Typical Usage Examples¶

Run VMC¶

champ/bin/vmc.mov1 -i vmc.inp -o vmc.out -e error

Run DMC¶

champ/bin/dmc.mov1 -i dmc.inp -o dmc.log -e error

Using MPI¶

For production calculations, you should use MPI.

mpirun -np 1024 champ/bin/vmc.mov1 -i dmc.inp -o dmc.out