--- trunk/tengDissertation/Introduction.tex 2006/04/12 21:20:13 2705 +++ trunk/tengDissertation/Introduction.tex 2006/04/13 04:47:47 2706 @@ -315,8 +315,7 @@ partition function like, isolated and conserve energy, Microcanonical ensemble(NVE) has a partition function like, \begin{equation} -\Omega (N,V,E) = e^{\beta TS} -\label{introEqaution:NVEPartition}. +\Omega (N,V,E) = e^{\beta TS} \label{introEquation:NVEPartition}. \end{equation} A canonical ensemble(NVT)is an ensemble of systems, each of which can share its energy with a large heat reservoir. The distribution @@ -771,8 +770,7 @@ _{1,h/2} , splitting gives a second-order decomposition, \begin{equation} \varphi _h = \varphi _{1,h/2} \circ \varphi _{2,h} \circ \varphi -_{1,h/2} , -\label{introEqaution:secondOrderSplitting} +_{1,h/2} , \label{introEquation:secondOrderSplitting} \end{equation} which has a local error proportional to $h^3$. Sprang splitting's popularity in molecular simulation community attribute to its @@ -955,11 +953,54 @@ for rigid body developed by Dullweber and his coworker \subsection{\label{introSection:lieAlgebra}Lie Algebra} +\subsection{\label{introSection:constrainedHamiltonianRB}Constrained Hamiltonian for Rigid Body} + +\begin{equation} +H = \frac{1}{2}(p^T m^{ - 1} p) + \frac{1}{2}tr(PJ^{ - 1} P) + +V(q,Q) + \frac{1}{2}tr[(QQ^T - 1)\Lambda ]. +\label{introEquation:RBHamiltonian} +\end{equation} +Here, $q$ and $Q$ are the position and rotation matrix for the +rigid-body, $p$ and $P$ are conjugate momenta to $q$ and $Q$ , and +$J$, a diagonal matrix, is defined by +\[ +I_{ii}^{ - 1} = \frac{1}{2}\sum\limits_{i \ne j} {J_{jj}^{ - 1} } +\] +where $I_{ii}$ is the diagonal element of the inertia tensor. This +constrained Hamiltonian equation subjects to a holonomic constraint, +\begin{equation} +Q^T Q = 1$, \label{introEquation:orthogonalConstraint} +\end{equation} +which is used to ensure rotation matrix's orthogonality. +Differentiating \ref{introEquation:orthogonalConstraint} and using +Equation \ref{introEquation:RBMotionMomentum}, one may obtain, +\begin{equation} +Q^t PJ^{ - 1} + J^{ - 1} P^t Q = 0 . \\ +\label{introEquation:RBFirstOrderConstraint} +\end{equation} + +Using Equation (\ref{introEquation:motionHamiltonianCoordinate}, +\ref{introEquation:motionHamiltonianMomentum}), one can write down +the equations of motion, +\[ +\begin{array}{c} + \frac{{dq}}{{dt}} = \frac{p}{m} \label{introEquation:RBMotionPosition}\\ + \frac{{dp}}{{dt}} = - \nabla _q V(q,Q) \label{introEquation:RBMotionMomentum}\\ + \frac{{dQ}}{{dt}} = PJ^{ - 1} \label{introEquation:RBMotionRotation}\\ + \frac{{dP}}{{dt}} = - \nabla _q V(q,Q) - 2Q\Lambda . \label{introEquation:RBMotionP}\\ + \end{array} +\] + + +\[ +M = \left\{ {(Q,P):Q^T Q = 1,Q^t PJ^{ - 1} + J^{ - 1} P^t Q = 0} +\right\} . +\] + \subsection{\label{introSection:DLMMotionEquation}The Euler Equations of Rigid Body Motion} -\subsection{\label{introSection:otherRBMotionEquation}Other Formulations for Rigid Body Motion} +\subsection{\label{introSection:symplecticDiscretizationRB}Symplectic Discretization of Euler Equations} -\section{\label{introSection:correlationFunctions}Correlation Functions} \section{\label{introSection:langevinDynamics}Langevin Dynamics} @@ -1168,3 +1209,5 @@ Body} \subsection{\label{introSection:centersRigidBody}Centers of Rigid Body} + +\section{\label{introSection:correlationFunctions}Correlation Functions}