Re: [AMBER] rism1d convergence query

From: Rakesh Srivastava <allahabad.21.gmail.com>
Date: Thu, 28 Jun 2018 11:32:32 +0530

Hello Tyler, I am still facing convergence issue. Can you suggest me
something for it, like a way to provide the numerical solver a starting
guess of solution from a previously converged calculation?

Thanks again.

Rakesh Srivastava
Research Fellow
School of Computational & Integrative Sciences
Jawaharlal Nehru University, New Delhi-110067
India



On Thu, Jun 28, 2018 at 10:30 AM Rakesh Srivastava <allahabad.21.gmail.com>
wrote:

> Thanks, Tyler for your help.
>
> Rakesh Srivastava
> Research Fellow
> School of Computational & Integrative Sciences
> Jawaharlal Nehru University, New Delhi-110067
> India
>
>
>
> On Wed, Jun 27, 2018 at 10:30 PM Tyler Luchko (Lists) <
> tluchko.lists.gmail.com> wrote:
>
>> Hi Rakesh,
>>
>> It sounds like you are trying to use a primitive model of an electrolyte
>> solution. This can be done with rism1d but you will need make some
>> adjustments. The dielectric constant you have set applies only if you have
>> a polar molecule, like water, in the solution. For the primitive model, you
>> should use theory=‘xrism’ and divide the charges of your ions by sqrt(78.5)
>> in the MDL file.
>>
>> If you are still having problems with convergence, please look at the
>> ‘Solution Convergence’ section of the manual on page 106.
>>
>> Hope this helps,
>>
>> Tyler
>>
>> > On Jun 26, 2018, at 11:14 PM, Rakesh Srivastava <allahabad.21.gmail.com>
>> wrote:
>> >
>> > Hello all,
>> >
>> > I want to perform rism1d calculation for a very asymmetrical ionic
>> system.
>> > I have prepared mdl parameters files for two asymmetric ions but the
>> > numerical procedure for rism1d does not converge rather the resid
>> parameter
>> > in out file shows oscillatory behavior (I am using KH closure and
>> > dielectric constant 78.5 but only two species in the system, no explicit
>> > water).
>> >
>> > My question is, whether there is a way to provide an initial guess for
>> > numerical solver from some previously converged less asymmetric system
>> so
>> > that the chances of convergence could be increased?
>> >
>> > Any help will really mean a lot.
>> >
>> > Thanks.
>> >
>> > Rakesh Srivastava
>> > Research Fellow
>> > School of Computational & Integrative Sciences
>> > Jawaharlal Nehru University, New Delhi-110067
>> > India
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>>
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Received on Wed Jun 27 2018 - 23:30:02 PDT
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