Re: [AMBER] How can I do a thermodynamic integration using Simpson's rules ?

From: Jinfeng Huang <>
Date: Tue, 2 Jun 2015 21:03:27 +0800 (CST)

Thanks for your reply! But I still puzzled whether the trapzoidal rule and the Simpson's rule share the same Gaussian integration. I have performed a TI MD with the trapzoidal rule, and now I want to calcu the free energy using simpson rule, should I need to do another TI MD with different lamda?
At 2015-06-02 17:43:52, "Hannes Loeffler" <> wrote:
>On Tue, 2 Jun 2015 17:20:25 +0800
>Jinfeng Huang <> wrote:
>> Dear amber users:
>> I want to use Simpson's rules to do a thermodynamic integration
>> using amber14. However I can only find statements about trapezoidal
>> rule in amber14 manual. So, I confused weather can achieve this goal
>> using amber14 and how to do it. Any help is highly appreciated!
>When you do TI you are calculating the gradient of the (potential)
>energy with respect to lambda. To obtain the free energy from this you
>need to integrate this in [0,1]. The trapzoidal rule, just like the
>Simpson's rule, are approximative techniques to compute an integral
>from discrete data. Various mathematical software or programming
>languages can do that.
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Received on Tue Jun 02 2015 - 06:30:02 PDT
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