Clarification on 1D reweighting from a 2D metadynamics simulation

[Mariana Yoshinaga]

Dear,

I performed a well-tempered metadynamics calculation with two CVs, whose plumed.dat content is described below. 

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WHOLEMOLECULES ENTITY0=1-16000 ENTITY1=38054-38062
lig_1: COM NOPBC ATOMS=38054-38062
d1: ZANGLES ATOMS1=38054,38059 MEAN
cos_theta: MATHEVAL ARG=d1.mean FUNC=cos(x) PERIODIC=NO
mem: COM NOPBC ATOMS=11-15886:125
CV1:  DISTANCE ATOMS=lig_1,mem SCALED_COMPONENTS

m: METAD ...
  ARG=CV1.c,cos_theta
  SIGMA=0.05,0.1         
  HEIGHT=0.28
  BIASFACTOR=10
  PACE=500
  TEMP=310
  GRID_MIN=-0.5,-1.0
  GRID_MAX=+0.5,+1.0
  GRID_BIN=200,200
  CALC_RCT
  RCT_USTRIDE=125
... m:

PRINT ARG=CV1.c,cos_theta,d1.mean,m.bias,m.rbias STRIDE=500 FILE=COLVAR

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I carried out a reweighting considering only CV1 and obtained a 1D FES plot. The content of reweight.dat is shown below:

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CV1: READ FILE=COLVAR IGNORE_TIME VALUES=CV1.c IGNORE_FORCES

m: READ FILE=COLVAR IGNORE_TIME VALUES=m.rbias IGNORE_FORCES

weights: REWEIGHT_METAD TEMP=310 ARG=m.rbias

hhcv1: HISTOGRAM ARG=CV1.c STRIDE=50 GRID_MIN=-0.5 GRID_MAX=+0.5 GRID_BIN=200 BANDWIDTH=0.005 LOGWEIGHTS=weights
ffcv: CONVERT_TO_FES GRID=hhcv1
DUMPGRID GRID=ffcv FILE=ffcv1.dat
PRINT ARG=CV1.c,weights STRIDE=1 FILE=COLVAR_reweight

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Does this procedure of reweighting with respect to only one CV make sense, even though the metadynamics was run using two CVs?  

Best regards,

Mariana Yoshinaga

[Michele Invernizzi]

Hi Mariana,

Yes this is correct and makes sense.

However, notice that if you bias is still moving a lot and hasn't reached the adiabatic limit, reweighting will fail and produce wrong results. They could be slightly wrong, as shown here https://pubs.acs.org/doi/10.1021/acs.jctc.2c00152, or completely wrong if you are very out of equilibrium.

Best,

Michele 

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