Use of Ewald Summation in MD++

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MD++: Use of the Ewald Summation

Eunseok Lee


Compile

In MD++, the BMB potential (short range interaction) + the Ewald summation (long range interaction) is implemented. You can download the source code from the repository of MD++, then use 'make' to compile the binary. 

> make bmb

When you complie it please notice that the link to FFTw package is required. Following parameters are used.


In principle, the Ewald summation must be same regardless of alpha, which just changes the speed of calculation. To check if the Ewald summation is calculated same, we can print out the energy and the Ewald summation for different Rcut (or alpha). In the source code, ewald.cpp, recover the commented out part (line #424 ~ #436), and then use 'MD++ eval' in script for different alphas. Use script file, [[Media: | ysz_Rcut_test.tcl]] , The result is like following.


From this result we can know that the safe range of R_cut is ~

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