Frequently Asked Questions

General questions, licensing

Is VASP included with AMS?

No, you need to provide your own VASP binary and license.

Are all VASP features supported?

No, only some common features as detailed in this manual are supported by the AMS interface.

How do I convert my old VASP inputs (up to AMS2025) to the new AMS2026 format?

AMSinput attempts to convert some of the input options, but there is no guarantee that it does so correctly. Double-check the input options carefully.

The program is always running in serial (using 1 core) ?

When running VASP through AMS, you need to set the environment variable SCM_DISABLE_MPI=1. This causes AMS to launch in serial and you will see a line like this at the top:

AMS 2024.101  RunTime: Apr10-2024 06:40:44  ShM Nodes: 1  Procs: 1

This is expected and intended. This line does not mean that VASP is running in serial.

At the top of VASP.log we can find more information about how many cores VASP is using:

running    4 mpi-ranks, on    1 nodes
distrk:  each k-point on    4 cores,    1 groups
distr:  one band on    1 cores,    4 groups
vasp.6.4.3 19Mar24 (build Oct  2 2025 12:09:38) complex

In this case, we see that VASP is actually running on 4 processor cores.

You can also monitor the CPU usage using top or other utilities.

Issues

With old versions of VASP (VASP 6.3 or older), Engine VASP automatically restarts the VASP process with a new plane wave basis set (ISTART=0, LWAVE=.FALSE.) when a change in the lattice is detected. This is done to prevent buildup of Pulay stress. Additionally, for certain calculations this may result in an overall speedup since there is no unnecessary writing of the WAVECAR.