--- trunk/chrisDissertation/dissertation.tex 2006/09/26 03:07:59 3023 +++ trunk/chrisDissertation/dissertation.tex 2006/10/11 14:33:13 3042 @@ -1,4 +1,4 @@ -\documentclass[12pt]{ndthesis} +\documentclass[nosummary]{ndthesis} % some packages for things like equations and graphics \usepackage[tbtags]{amsmath} @@ -11,13 +11,15 @@ \usepackage{cite} \usepackage{enumitem} \renewcommand{\appendixname}{APPENDIX} +\clubpenalty=10000 +\widowpenalty=10000 \begin{document} \frontmatter \title{DEVELOPMENT OF MOLECULAR DYNAMICS TECHNIQUES FOR THE -STUDY OF WATER AND OTHER BIOCHEMICAL SYSTEMS} +STUDY OF WATER AND BIOCHEMICAL SYSTEMS} \author{Christopher Joseph Fennell} \work{Dissertation} \degprior{B.Sc.} @@ -31,66 +33,46 @@ classical molecular simulations, with particular empha This dissertation comprises a body of research in the field of classical molecular simulations, with particular emphasis placed on -the proper depiction of water. This work is arranged such that the -techniques and models used within are first developed and tested -before being applied and compared with experimental results. With this -organization in mind, it is appropriate that the first chapter deals -primarily the technique of molecular dynamics and technical -considerations needed to correctly perform molecular simulations. +the proper depiction of water. It is arranged such that the techniques +and models are first developed and tested before being applied and +compared with experimental results. Accordingly, the first chapter +starts by introducing the technique of molecular dynamics and +discussing technical considerations needed to correctly perform +molecular simulations. -Building on this framework, the second chapter discusses correction -techniques for handling the long-ranged electrostatic interactions -common in molecular simulations. Particular focus is placed on a -shifted-force ({\sc sf}) modification of the damped shifted Coulombic -summation method. In this work, {\sc sf} is shown to be nearly -equivalent to the more commonly utilized Ewald summation in -simulations of condensed phases. Since the {\sc sf} technique is -pairwise, it scales as $\mathcal{O}(N)$ and lacks periodicity -artifacts introduced through heavy reliance on the reciprocal-space -portion of the Ewald sum. The electrostatic damping technique used -with {\sc sf} is then extended beyond simple charge-charge -interactions to include point-multipoles. Optimal damping parameter -settings are also determined to ensure proper depiction of the -dielectric behavior of molecular systems. Presenting this technique -early enables its application in the systems discussed in the later -chapters and shows how it can improve the quality of various molecular -simulations. +The second chapter builds on these consideration aspects by discussing +correction techniques for handling long-ranged electrostatic +interactions. Particular focus is placed on the damped shifted force +({\sc sf}) technique, and it is shown to be nearly equivalent to the +Ewald summation in simulations of condensed phases. Since the {\sc sf} +technique is pairwise, it scales as $\mathcal{O}(N)$ and lacks +periodicity artifacts. This technique is extended to include +point-multipoles, and optimal damping parameters are determined to +ensure proper depiction of the dielectric behavior of molecular +systems. The third chapter applies the above techniques and focuses on water model development, specifically the single-point soft sticky dipole (SSD) model. In order to better depict water with SSD in computer -simulations, it needed to be reparametrized. This work results in the -development of SSD/RF and SSD/E, new variants of the SSD model -optimized for simulations with and without a reaction field -correction. These new single-point models are more efficient than the -common multi-point partial charge models and better capture the -dynamic properties of water. SSD/RF can be successfully used with -damped {\sc sf} through the multipolar extension of the technique -described in the previous chapter. Discussion on the development of -the two-point tetrahedrally restructured elongated dipole (TRED) water -model is also presented, and this model is optimized for use with the -damped {\sc sf} technique. Though there remain some algorithmic -complexities that need to be addressed (logic for neglecting -charge-quadrupole interactions between other TRED molecules) to use -this model in general simulations, it is approximately twice as -efficient as the commonly used three-point water models (i.e. TIP3P -and SPC/E). +simulations, it needed to be reparametrized, resulting in SSD/RF and +SSD/E, new variants optimized for simulations with and without a +reaction field correction. These new single-point models are more +efficient than the more common multi-point models and better capture +the dynamic properties of water. SSD/RF can be used with damped {\sc +sf} through the multipolar extension described in the previous +chapter. -Continuing in the direction of model applications, the final chapter -deals with a unique polymorph of ice that was discovered while -performing water simulations with the fast simple water models -discussed in the previous chapter. This form of ice, called -``imaginary ice'' (Ice-$i$), has a low-density structure which is -different from any known polymorph observed in either experiment or -computer simulation studies. The free energy analysis discussed here -shows that this structure is in fact the thermodynamically preferred -form of ice for both the single-point and commonly used multi-point -water models under the chosen simulation conditions. It is shown that -inclusion of electrostatic corrections is necessary to obtain more -realistic results; however, the free energies of the various -polymorphs (both imaginary and real) in many of these models is shown -to be so similar that choice of system properties, like the volume in -$NVT$ simulations, can directly influence the ice polymorph expressed. +The final chapter deals with a unique polymorph of ice that was +discovered while performing simulations with the SSD models. This +form of ice, called ``imaginary ice'' (Ice-$i$), has a low-density +structure which is different from any previously known ice +polymorph. The free energy analysis discussed here shows that it is +the thermodynamically preferred form of ice for both the single-point +and commonly used multi-point water models. Including electrostatic +corrections is necessary to obtain more realistic results; however, +the free energies of the studied polymorphs are typically so similar +that system properties, like the volume in $NVT$ simulations, can +directly influence the ice polymorph expressed. \end{abstract} @@ -106,16 +88,15 @@ teacher and helped fuel my desire to learn. I would al I would to thank my advisor, J. Daniel Gezelter, for the guidance, perspective, and direction he provided during this work. He is a great teacher and helped fuel my desire to learn. I would also like to thank -my fellow group members - Dr.~Matthew A.~Meineke, Dr.~Teng Lin, -Charles F.~Vardeman~II, Kyle Daily, Xiuquan Sun, Yang Zheng, Kyle -S.~Haygarth, Patrick Conforti, Megan Sprague, and Dan Combest for -helpful comments and suggestions along the way. I would also like to -thank Christopher Harrison and Dr. Steven Corcelli for additional -discussions and comments. Finally, I would like to thank my parents, -Edward P.~Fennell and Rosalie M.~Fennell, for providing the -opportunities and encouragement that allowed me to pursue my -interests, and I would like to thank my wife, Kelley, for her -unwavering support. +my fellow group members - Dr.~Matthew Meineke, Dr.~Teng Lin, Charles +Vardeman~II, Kyle Daily, Xiuquan Sun, Yang Zheng, Kyle Haygarth, +Patrick Conforti, Megan Sprague, and Dan Combest for helpful comments +and suggestions along the way. I would also like to thank Christopher +Harrison and Dr.~Steven Corcelli for additional discussions and +comments. Finally, I would like to thank my parents, Edward and +Rosalie Fennell, for providing the opportunities and encouragement +that allowed me to pursue my interests, and I would like to thank my +wife, Kelley, for her unwavering support. \end{acknowledge} \mainmatter