Hi all,
I am trying to build a liquid mixture containing perchlorate anions (ClO₄⁻), Na⁺ ions, acetonitrile, DMSO, water, and benzaldehyde (BAL) using the OPLS-AA 2024 force field in EMC.
EMC works correctly on my PC for common molecules such as DMSO, ACN, water, and BAL. However, when I add ClO₄⁻, EMC stops with missing-rule errors:
Warning: no rule found for {group, site} = {CLO4, 0}.
Warning: no rule found for {group, site} = {CLO4, 1}.
Warning: no rule found for {group, site} = {CLO4, 2}.
Warning: no rule found for {group, site} = {CLO4, 3}.
Warning: no rule found for {group, site} = {CLO4, 4}.
Error: core/fields.c:433 FieldsApply:
Missing rules.
Program aborted.
My current .esh input is:
#=======================================================
ITEM OPTIONS
replace true
field opls-aa
number true
field_charge false
density 0.3
focus true
build_dir .
ITEM END
#=======================================================
ITEM SHORTHAND
BAL:c=o [c-0.09]1([H+0.09])[c-0.09]([H+0.09])[c-0.09]([H+0.09])[c+0.04]([c-0.09]([H+0.09])[c-0.09]1([H+0.09]))[c+0.39]([H+0.00])=[O-0.43],10
SPCE:c=o [O-0.848]([H+0.424])([H+0.424]),40
ACN:c=o [C-0.233]([H+0.108])([H+0.108])([H+0.108])[C+0.402]#[N-0.493],10
NA:c=o [Na+1.000],10
CLO4:c=o [Cl+1.4]([O-0.6])([O-0.6])([O-0.6])([O-0.6]),10
ITEM END
#=======================================================
For reference, I have attached the relevant OPLS-AA field files which I use for making acetonitrile, DMSO, and BAL.
I am still a beginner with EMC, so I am unsure how to properly add a new molecule type to the OPLS-AA field files. Could anyone advise which entries should be added to the EMC OPLS-AA .define, .top, and .prm files to support atomistic ClO₄⁻?
Any guidance or example of adding a new ion or molecule to EMC would be greatly appreciated.
Thank you.
opls-aa.define (105.6 KB)
opls-aa.prm (65.4 KB)
opls-aa.top (18.3 KB)