Coarse Grained Molecular Dynamics (CGMD) 為分子動力學(MD)的一種延伸方法。此法能夠藉由擷取一團原子群重要特徵之方式，來達到以較少的節點數取代多數原子做運算之目的。因此CGMD不但能夠比MD節省運算時間，在多尺度的模擬上(multi-scale simulation)，更能針對其物理特性的不同，靈活的對系統做適當的尺度變換。

　　CGMD法簡化粒子數的方式主要是源自於有限元素法概念，其運動方程式的推導乃是由MD法經由統計力學之處理所求得，所以CGMD在處理多尺度問題時，由於系統內不同尺度仍處於相同的理論基礎，因此能夠成功解決跨尺度模擬時在接合面所產生之不連續問題。

　　雖然CGMD 擁有簡化粒子數與變換尺度之優點，但此法之發展仍處於發展階段，而尋找適當方法來正確描述節點勢能將是解決CGMD法限制之關鍵。本研究中除將CGMD法做更完整的理論推導外，更將CGMD法運用於奈米壓痕上，並將得到的結果與MD做比較。

　　經過電腦模擬後可以得到如下結論:(1)CGMD與MD在奈米壓痕的變形機制與物理行為是很接近的。(2)由CGMD力量位移曲線所估算的薄膜基板材料性質較MD略高一些。(3)CGMD模擬時間約為MD的1/5~1/10。

　Coarse Grained Molecular Dynamics (CGMD) is a technique for simulation extended from Molecular Dynamics (MD). It captures the important atomistic effects with fewer nodes instead of atoms so that CGMD can not only effectively save more computational cost than MD but it also can vary its scale to describe the system more appropriate in multi-scales simulation.

　The concept of CGMD utilizes Finite Element Method (FEM) to reduce the number of atoms. And the equations of motion are derived directly from MD through a statistical procedure so that the different scales are run concurrently with the same model in multi-scale simulation. Therefore, this allows a seamless coupling of length scales.

　Despite its above advantages above mentioned, CGMD model is still in development. The determination of appropriate potential function for describing the CGMD model is the key to solve the limitations. This paper not only derive the CGMD theory, but also implement this theory to nanoindentation. Moreover, simulation results are compared with MD.

　After computer simulations, We have some conclusions and are listed as follows: (1) The physical phenomenon of nanoindentation deformation computed by CGMD and MD methods are very close. (2) The Young’s modulus and hardness predicted by CGMD are a little bit higher than MD. (3) The computational time of CGMD is only one-fifth to one-tenth as long as MD.

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