Dear Amber experts:
I am new to parameter fitting area, and have some fundamental questions
hoping anyone can help with. It may be boring to answer these such
fundamental questions, so any suggested reference or searching direction
would be greatly appreciated.
1. If the optimized bond parameters(for torsion term) are negative, are
those parameters is reasonable (of chemical meaning )? Dose it means the
calculation didn’t converged to global minimum and need continuous
optimization ?
2. what is the criteria or reference for function value? Like for 27
dimensions?
3. How many input structure would be good enough for 27 dimensions fitting
(for torsion term)?
4. How can I make sure that the optimized parameters is good enough to do
simulations? Or How to make sure the calculation converged to the global
minimum? One way I know is to redo the calculation with the same input
structures and quantum energy data to make sure get the same optimized
parameters, is that right?
5. Excepting increase input structures or change the algorithm and other
function parameters, is there any other suggested way to help the
calculation converged to global minimum?
6. For a stiffness ring structure(like conjugated 5 mem ring), can I
optimize the dihedral within the ring structure? Because when I include
that dihedral , the fitting cannot converge (calculation up to two
days). But if I exclude that dihedral, it can easily converge. But the
function value is too large, Function value with fitted parameters =
15578.0208, R^2 = 0.9808. so I don’t know the problem is due to the
bad input data or I just cannot optimize that dihedral
And attached my fitting input files and output files.
Thanks in advance!
Thank you,
Tingting
Sent from [1]Mail for Windows 10
References
1.
https://go.microsoft.com/fwlink/?LinkId=550986
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Received on Thu Apr 09 2020 - 22:00:02 PDT
