Re: [AMBER] R.E.D, alkene isostere, Gly-Pro, P9501

From: Cecilia Lindgren <cecilia.lindgren.chem.umu.se>
Date: Mon, 13 Jan 2014 08:57:36 +0100

Ok, thank you very much!
I have uploaded another project for this isostere now, and I will definitely try R.E.DD.B. once this last one is finished.

Best regards,
Cecilia

-----Original Message-----
From: FyD [mailto:fyd.q4md-forcefieldtools.org]
Sent: den 10 januari 2014 08:38
To: AMBER Mailing List
Cc: fan.wang.u-picardie.fr
Subject: Re: [AMBER] R.E.D, alkene isostere, Gly-Pro, P9501

Dear Cecilia,

It looks like you study a bunch of different dipeptide analogs; you could study all of them one by one using R.E.D. Server Dev. and then once 'all' correctly defined you could rerun a job, which would include all your dipeptide analogs, and generate an entire FF for all these molecules _and_ fragments ready to be validated/used in MD simulations. I would be happy if you would accept to submit this large project in R.E.DD.B. once all fully defined.

I looked at your Gly-Pro analogs using:
http://cluster.q4md-forcefieldtools.org/~x/Project/P9501/javaappletmol2-4.html
  (x your cluster account; hidden for this email)

I am not a big fan ;-) of one atom type generated by R.E.D. Python in this P9501 job: I would replace CA by CM in this case; we will correct that; sorry for that...

A quick workaround until we correct this bug: just provide the full list of FF atom types you want to use using:
MOLECULE1-ATMTYPE = your choice...
see
http://q4md-forcefieldtools.org/REDS-Development/Demo2-Files/Project.config

> I am trying to calculate charges for an alkene amide bond isostere
> for the dipeptide fragment Gly-Pro. By analogy I added the following
> information in a frcmod.user file:
>
> ANGLE
> CM-CA-CT 70.0 119.70 Source (from CM-CM-CT)

as you can see you corrected by yourself ;-) CM-CA should be CM-CM

> CT-CA-CT 50.0 118.00 Source (from CT-N-CT)

for CT-CM-CT I would prefer to use CT-C -CT by analogy i.e. keeping the same element; CM = C and not CM = N

> CA-CM-CT 70.0 119.70 Source (from CM-CM-CT)

will become CM-CM-CT and it is known

> C-CT-CA 63.0 110.10 Source (from C-CT-N)

same remark as above; and '63' could become '65'...

> CM-CT-N 63.0 110.10 Source (from C-CT-N)

same remark as above

More generally you could run R.E.D. Python using:
MEPTHOD_OPTCALC = "B3LYP"
BASSET_OPTCALC = "6-311+G(d,p)"
see
http://q4md-forcefieldtools.org/REDS-Development/Demo2-Files/Configuration.py
to generate an optimized geometry generated using a larger theory level and use ONLY the optimized geometry generated to ONLY determine the equilibrium values of the unknown FF parameters listed in frcmod.unknown

> IMPROPER
> CM-CT-CA-CT 1.0 180.0 2 Source

i.e. will become CM-CT-CM-CT and consequently it should be found by R.E.D. Python using X -X -CM-HA

> My question is: what information would you recommend that I use for
> IMPROPER: CM-CT-CA-CT? Here I have based it on C-CM-N*-CT, but I am
> not convinced that it is ok, but I have not found any other that I
> like better either... I am using amber99sb.

see above...

I hope this helps,
regards, Francois



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Received on Mon Jan 13 2014 - 00:00:03 PST
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