Dear colleagues,

I am having this problem when running the Umbrella Sampling tutorial. Can anyone give me a hand? Starts at Step 3. Thank you.

WARNING 1 [file topol.top, line 54]:

The GROMOS force fields have been parametrized with a physically

incorrect multiple-time-stepping scheme for a twin-range cut-off. When

used with a single-range cut-off (or a correct Trotter

multiple-time-stepping scheme), physical properties, such as the density,

might differ from the intended values. Since there are researchers

actively working on validating GROMOS with modern integrators we have not

yet removed the GROMOS force fields, but you should be aware of these

issues and check if molecules in your system are affected before

proceeding. Further information is available at

https://redmine.gromacs.org/issues/2884 , and a longer explanation of our

decision to remove physically incorrect algorithms can be found at

https://doi.org/10.26434/chemrxiv.11474583.v1 .

NOTE 2 [file topol.top, line 54]:

System has non-zero total charge: -10.000000

Total charge should normally be an integer. See

http://www.gromacs.org/Documentation/Floating_Point_Arithmetic

for discussion on how close it should be to an integer.

Analysing residue names:

There are: 135 Protein residues

There are: 10727 Water residues

Analysing Protein...

Number of degrees of freedom in T-Coupling group rest is 67749.00

NOTE 3 [file ions.mdp]:

You are using a plain Coulomb cut-off, which might produce artifacts.

You might want to consider using PME electrostatics.

This run will generate roughly 3 Mb of data

There were 3 notes

There was 1 warning

-------------------------------------------------------

Program: gmx grompp, version 2020.4

Source file: src/gromacs/gmxpreprocess/grompp.cpp (line 2353)

Fatal error:

Too many warnings (1).

If you are sure all warnings are harmless, use the -maxwarn option.

For more information and tips for troubleshooting, please check the GROMACS

website at http://www.gromacs.org/Documentation/Errors