Error running gmx bar file ABC.xvg contains multiple sets but no indication of the native l

User discussions
1

GROMACS version: 2024.2
GROMACS modification: No

I am running an npt to generate input for gmx energy. I have written individual files for npt.0 , npt.1 etc for lambda 0,1,2 resp. The FEP portion of the npt.0 isfree_energy = yes
init_lambda_state = 0
delta_lambda = 0
calc_lambda_neighbors = 1
vdw_lambdas = 0.0
coul_lambdas = 0.0
sc-alpha = 0.5
;sc-function =beutler
sc-coul = yes
sc-power = 1
sc-sigma = 0.3
couple-moltype = Ligand
couple-lambda0 = vdwq
couple-lambda1 = q
couple-intramol = no
nstdhdl = 50

the gmx energy produces the output e.g.
view 0.15, 0.15, 0.75, 0.85
@ legend on
@ legend box on
@ legend loctype view
@ legend 0.78, 0.8
@ legend length 2
@ s0 legend “Potential”
@ s1 legend “Total Energy”
@ s2 legend “dVcoul/dl”
@ s3 legend “dVvdw/dl”
0.000000 -361905.687500 -294077.406250 -80.033150 -22.859303
1.500000 -353951.875000 -284405.000000 -10.672368 -43.508614
3.000000 -349970.562500 -280267.750000 -4.409541 51.939854
4.500000 -350202.437500 -280141.187500 -17.767170 69.356506
6.000000 -348927.562500 -278860.125000 -4.000705 90.504128
7.500000 -348938.906250 -279196.718750 -19.596489 64.442612
…
…

Using gmx bar produces an error: “File ABC.lambda.0.xvg contains multiple sets but no indication of the native lambda”

I can find almost nothing describing the error . Various renditions of the npt FEP portion have been explored including listing all lambda values and using other individual states.

Can anyone point to the source of the error ?

regards,
pb

2

There is only one lambda state in the files, so it cannot calculate differences to neighbouring lambda states. You say that you have already tried listing all lambda values, but I would still recommend something like:

...
init_lambda_state = 0 ; This should be different for all (11) simulations
delta_lambda = 0
calc_lambda_neighbors = 1
vdw_lambdas = 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
...

Also, you can use the ener.edr files as input to gmx bar directly, using the -g input option.