# Gas or Vacuum phase

**URL:** <https://gromacs.bioexcel.eu/t/gas-or-vacuum-phase/4387>\
**Category:** User discussions\
**Tags:** mdp-parameters\
**Created:** [June 29, 2022, 9:43pm UTC](https://gromacs.bioexcel.eu/t/gas-or-vacuum-phase/4387 "2022-06-29T21:43:27Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![dr\_m\_ganj](https://avatars.discourse-cdn.com/v4/letter/d/9f8e36/32.png) [@dr\_m\_ganj](https://gromacs.bioexcel.eu/u/dr_m_ganj)\
**Post date:** [June 29, 2022, 9:43pm UTC](https://gromacs.bioexcel.eu/t/gas-or-vacuum-phase/4387/1 "2022-06-29T21:43:27Z")

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GROMACS version: 2018  
GROMACS modification: Yes/No  
Dear Justin Lemkul,  
Is it true that for gas phase simulation cutoff mustn’t be applied? It means that rlist = rcoulomb = rvdw = 0 as well as nstlist = 0? And must it be done in NVT ensemble with doing PBC condition?

Best regards,  
ganj

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**Author:** ![jalemkul](https://dub1.discourse-cdn.com/flex017/user_avatar/gromacs.bioexcel.eu/jalemkul/32/18_2.png) [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)\
**Post date:** [July 1, 2022, 2:30am UTC](https://gromacs.bioexcel.eu/t/gas-or-vacuum-phase/4387/2 "2022-07-01T02:30:41Z")

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GROMACS no longer supports cutoffs set to zero, as it required the group nonbonded scheme. The only way to do these calculations in current versions is to set a very large box, use very large cutoffs (sufficient to encompass all nonbonded pairs) and apply an NVT ensemble.