-nots crashes with "file not found ... ts/nmode" in mcsimu.f90:349, regardless of rate-constant method

[sreekanth221998]

Version

v1.2.0 (binary release)

Steps to reproduce

qcxms2 in.xyz -T 4 -nots

or, to rule out the rate-constant method:
qcxms2 in.xyz -T 4 -nots -rrkm

Actual behavior

Crashes immediately:
forrtl: severe (29): file not found, unit -129, file /p1/ts/nmode
Image PC Routine Line Source
qcxms2 00000000004186A5 Unknown Unknown Unknown
qcxms2 000000000049B2E5 iomod_mp_rdshort_ 434 iomod.f90
qcxms2 000000000046FB90 mcsimu_mp_monteca 349 mcsimu.f90
qcxms2 00000000004A5941 fragmentation_mp_ 249 fragmentation.f90
qcxms2 0000000000403FE2 MAIN__ 181 main.f90

Confirmed via strace that ORCA is never invoked (0 calls) before this — it fails before any transition-state work would happen, on both a plain neutral test molecule and with -rrkm.

Root cause

In src/mcsimu.f90, the barrier-reading loop correctly branches on env%nots:

if (env%nots) then
   barriers(i) = de(i)      ! correctly skips barrier_/ircmode_ files
else
   call rdshort_real(...'/barrier_'//trim(env%tslevel), barriers(i))
   call rdshort_real(...'/ircmode_'//trim(env%geolevel), irc(i))
   ...
end if
but the thermal-correction loop right after it does not:


call rdshort_int(trim(env%path)//"/"//trim(fragdirs(j, 1))//"/ts/nmode", nmode)   ! line 349, unconditional
ts/nmode is only ever written when a real TS search runs. -nots skips that entirely, so this read always fails, regardless of which rate-constant method (-rrkm/-eyring) is selected downstream.

<Suggested fix>
Guard this block (and the xtbthermo call it feeds into dgeas) with if (.not. env%nots). For the env%nots case, skip the TS-derived thermal correction entirely, e.g. dgeas(:) = barriers(j) — consistent with -nots already meaning `use the raw reaction energy, no TS-derived correction`.

[roman-bushuiev]

Hi @sreekanth221998, I am facing the same issue when running QCxMS2 without ORCA and with -nots enabled. The program searches for p*/ts/nmode files that do not exist, because the TS search is skipped. I would like to try your fork (PR) to see if it resolves the issue. Is it ready to be tested?

[sreekanth221998]

Hi @sreekanth221998, I am facing the same issue when running QCxMS2 without ORCA and with -nots enabled. The program searches for p*/ts/nmode files that do not exist, because the TS search is skipped. I would like to try your fork (PR) to see if it resolves the issue. Is it ready to be tested?

It's working, I have tested with one SMILES