Running and Verification

Procedure

Use PuTTY to log in to the server as the root user.
Create a working directory and go to it.
```
mkdir -p /path/to/CASE
cd /path/to/CASE
```
Prepare the test case file vasp-small.gz and copy it to the /path/to/CASE directory.

Deploy the test case.

cd /path/to/CASE
tar -vxf vasp-small.gz
cd vasp.Hg
mv IN-long INCAR

Set the environment variables.

export PATH=/path/to/VASP/vasp.5.4.4/bin:$PATH

Create a host file.
```
vi hostfile
```
Press i to enter the insert mode and add the following content:
```
node1
node2
```
node1 and node2 are the names of the nodes where the code is executed. Change them based on your requirements and ensure that the nodes can ping each other. Enable SSH password-free login between the nodes.
Press Esc, type :wq!, and press Enter to save the file and exit.
Start the VASP program.
- Multiple nodes
```
mpirun --allow-run-as-root -np 16 -N 8 -x OMP_NUM_THREADS=1 -x PATH=$PATH -x LD_LIBRARY_PATH=$LD_LIBRARY_PATH --hostfile hostfile vasp_std 2>&1 | tee -a vasp.out
```
  If the information shown in the following figure is displayed at the end of the OUTCAR log generated by VASP, the VASP program stops properly.
- Single node
```
mpirun --allow-run-as-root -np 16 -x OMP_NUM_THREADS=1 vasp_std 2>&1 | tee -a vasp.out
```
  If the information shown in the following figure is displayed at the end of the OUTCAR log generated by VASP, the VASP program stops properly.
  - The -np parameter indicates the total number of processes. The -N parameter indicates the number of processes running on each node. Here, two nodes are used as an example. Change the setting based on the actual host configuration. Alternatively, you do not need to specify the two parameters and the maximum number of processes will be used.
  - The -x OMP_NUM_THREADS parameter indicates the number of threads to be used.
  - Check the value of real time (unit: second) in the OUTCAR log. A smaller value indicates higher performance.

Parent topic: VASP 5.4.4 Porting Guide (openEuler 21.03)