Hello everyone,
I am using EMC to build an initial configuration for an epoxy resin crosslinking simulation in LAMMPS (using DDCC Xlinker). My system consists of DGEBA and 4,4’-Dithiodianiline (AFD) using the PCFF force field.
I am running EMC on Windows (version 9.4.4, build Jul 21 2026).
When I try to build the system, EMC crashes at 0% during the building phase with the following error:
Error: core/types/inverse/angle.c:462 InverseAngleInit:
Cutoff not reached for [c:cp:cp].
Program aborted.
What I found out so far:
-
The crash happens mathematically whenever there is an aliphatic carbon attached to an aromatic ring (e.g., the quaternary carbon in DGEBA, or even a simple Toluene molecule:
Cc1ccccc1). -
Molecules without this specific connection, like pure Benzene or AFD (which has N and S attached to the aromatic rings, but no aliphatic C), build perfectly without any errors.
-
If I temporarily comment out the
#quartic_angleparameter forc cp cpinsidepcff.frc, EMC bypasses the crash and builds the structure successfully (though obviously, the parameter is missing for LAMMPS). -
Setting the density very low (e.g.,
density 0.1) is necessary to prevent steric clashes for the epoxy rings, but it does not prevent this specificInverseAngleInitcrash. -
I noticed a similar issue reported recently for
[c:c_1:o_1]in the same Windows build, which was suspected to be a compiler/math bug on Windows.
Additionally, once the [c:cp:cp] issue is bypassed, the parser complains about missing angle parameters for the epoxy ring attached to the aliphatic chain (e.g., [c:o3e:c3h]). It seems PCFF is missing some parameters for substituted epoxies.
I’ll attach my .esh file:
ITEM OPTIONS
replace true
mass true
number true
#ntotal 45000
density 0.55
field pcff
charge true
build_dir .
#radius 6
#emc_execute true
ITEM END
ITEM GROUPS
dgeba CC(C)(C1=CC=C(C=C1)OCC2CO2)C3=CC=C(C=C3)OCC4CO4
afd C1=CC(=CC=C1N)SSC2=CC=C(C=C2)N
cross_mol C1=CC=CC=C1OCC(O)CNC2=CC=CC=C2
ITEM END
ITEM CLUSTERS
dgeba dgeba,685
afd afd,411
cross_mol cross_mol,1
ITEM END
Is there a proper way to fix the Cutoff not reached error on Windows without switching to WSL/Linux? And how should I properly handle the missing [c:o3e:c3h] parameters for DGEBA in PCFF?
Also with an older version of EMC (from March 2024), this exact same script and system built perfectly with zero issues. The problem seems to be a regression introduced in this newer July 2026 Windows build.
Thank you in advance for your help!