Polymer(Korea) (폴리머)

The Polymer Society of Korea (한국고분자학회)
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Molecular Simulation Studies for Penetrable-Sphere Model: II. Collision Properties

침투성 구형 모델에 관한 분자 전산 연구: II. 충돌 특성

  • Kim, Chun-Ho (Department of Chemical Engineering, Keimyung University) ;
  • Suh, Soong-Hyuck (Department of Chemical Engineering, Keimyung University)
  • 김춘호 (계명대학교 화학공학과) ;
  • 서숭혁 (계명대학교 화학공학과)
  • Received : 2011.01.27
  • Accepted : 2011.06.15
  • Published : 2011.11.25
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Abstract

Molecular simulations via the molecular dynamics method have been carried out to investigate the dynamic collision properties of penetrable-sphere model fluids. The collision frequencies, the mean free paths, the angle distributions of the hard-type reflection and the soft-type penetration, and the effective packing fractions are computed over a wide range of the packing fraction ${\phi}$ and the repulsive energy ${\varepsilon}^*$. The soft-type collisions are dominated for lower repulsive energy systems, while the hardtype collisions for higher repulsive energy systems. Very interestingly, the ratio of the soft-type (or, the hard-type) collision frequency to the total collision frequency is directly related with the Boltzmann factor of acceptance (or rejection) probabilities in the canonical ensemble Monte Carlo calculations. Such dynamic collision properties are shown to be restricted for highly repulsive and dense systems of ${\varepsilon}^*{\geqq}3.0 $and ${\phi}{\geqq}0.7$, indicating the cluster forming structures in the penetrable-sphere model.

침투 가능한 구형 모델 유체의 충돌 특성을 고찰하고자 분자 동력학 방법을 이용한 전산 모사를 수행하였다. 이로부터 다양한 범위의 입자 충전 분율 ${\phi}$ 및 척력적 에너지 ${\varepsilon}^*$ 조건에 대한 충돌 빈도수, 평균 자유 행로, 강체형 반사 충돌각 및 연체형 침투 충돌각의 분포도, 유효 충전 분율 등을 계산하였다. 낮은 척력적 에너지 조건에서는 연체형 충돌이 주된 특성이나, 반면 높은 척력적 에너지 조건에서는 강체형 충돌이 주된 요인이었다. 매우 흥미롭게도, 전체 충돌 빈도수에 대한 연체형 충돌비(또는, 강체형 충돌비)는 정준 앙상블의 몬테카를로 전산 모사에서 받아들임 확률(또는, 되돌림 확률)로 표시되는 볼쯔만 인자와 직접적으로 관계되었다. 이와 같은 거동 입자들의 동적 충돌 특성들은 ${\varepsilon}^*{\geqq}3.0$ 및 ${\phi}{\geqq}0.7$ 범위의 높은 척력적 에너지 및 높은 충전 분율 조건에서 제한적이었으며, 이는 침투성 구형 모델에서 나타나는 클러스터 형성 구조를 함축하고 있다.

Keywords

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