username@computername:~/stack$ ls -l
total 12
-rw-r--r-- 1 username username 813 Dec 25 16:38 circle.geo
-rw-r--r-- 1 username username 585 Dec 26 19:31 input
-rw-r--r-- 1 username username 1063 Dec 27 17:16 stack.mat
username@computername:~/stack$ vampire-serial
_
(_)
__ ____ _ _ __ ___ _ __ _ _ __ ___
\ \ / / _` | '_ ` _ \| '_ \| | '__/ _ \
\ V / (_| | | | | | | |_) | | | | __/
\_/ \__,_|_| |_| |_| .__/|_|_| \___|
| |
|_|
Version 7.0.0 Dec 27 2025 17:26:35
Git commit: fed31aa8d06f278d43089352e126350bfdca26f2
Licensed under the GNU Public License(v2). See licence file for details.
Developers: Richard F L Evans, Sarah Jenkins, Andrea Meo,
Daniel Meilak, Andrew Naden, Matthew Ellis,
Oscar Arbelaez, Sam Morris, Rory Pond, Weijia Fan,
Phanwadee Chureemart, Pawel Sobieszczyk, Joe Barker,
Thomas Ostler, Andreas Biternas, Roy W Chantrell,
Wu Hong-Ye, Razvan Ababei, Sam Westmoreland,
Milton Persson
Compiler Flags:
Vampire includes a copy of the qhull library from C.B. Barber and The
Geometry Center and may be obtained via http from
www.qhull.org.
================================================================================
Sat Dec 27 18:34:47 2025
================================================================================
Initialising system variables
Creating system
Generating neighbour list..........done!
Copying system data to optimised data structures.
Using generic/normalised form of exchange interaction with 6 total interactions.
Number of atoms generated: 29240
Starting Simulation with Program Hysteresis-Loop...
Simulation run time [s]: 101.766
Simulation ended gracefully.
username@computername:~/stack$ ~/vampire/util/vdc/vdc --xyz
|------------------------------------------------------------|
| Vampire Data Converter for v5+ |
|------------------------------------------------------------|
Processing snapshot 00000000
...
Processing snapshot 00000029
username@computername:~/stack$ rasmol -xyz
crystal.xyz 
I may have found a way to improve the code to have it work. I have attached a patch file for it (filename: system_type.patch). Of note, use it at your own risk as more testing or verification may be needed.