![]() To validate and optimize the parameters, we calculated hydration free energies of the solvated ions and also lattice energies (LE) and lattice constants (LC) of alkali halide salt crystals. To provide a more appropriate balance, we reoptimized the parameters of the Lennard-Jones potential for the ions and specific choices of water models. The likely cause of the artifact in the AMBER parameters relates to the naive mixing of the Smith and Dang chloride parameters with AMBER-adapted Åqvist cation parameters. Our starting point centered on observations from long simulations of biomolecules in salt solution with the AMBER force fields where salt crystals formed well below their solubility limit. The applied methodology is general and can be extended to other ions and to polarizable force-field models. Although it has been clearly demonstrated that truly accurate treatments of ions will require inclusion of nonadditivity and polarizability (particularly with the anions) and ultimately even a quantum mechanical treatment, our goal was to simply push the limits of the additive treatments to see if a balanced model could be created. In this work, we describe our efforts to build better models of the monovalent ions within the pairwise Coulombic and 6-12 Lennard-Jones framework, where the models are tuned to balance crystal and solution properties in Ewald simulations with specific choices of well-known water models. ![]() At present, the best force fields for biomolecules employ a simple additive, nonpolarizable, and pairwise potential for atomic interaction. A good model needs to simultaneously reproduce many properties of ions, including their structure, dynamics, solvation, and moreover both the interactions of these ions with each other in the crystal and in solution and the interactions of ions with other molecules. To properly model ionic interaction and stability in atomistic simulations of biomolecular structure, dynamics, folding, catalysis, and function, an accurate model or representation of the monovalent ions is critically necessary. Continued abuse of our services will cause your IP address to be blocked indefinitely.Alkali (Li +, Na +, K +, Rb +, and Cs +) and halide (F −, Cl −, Br −, and I −) ions play an important role in many biological phenomena, roles that range from stabilization of biomolecular structure, to influence on biomolecular dynamics, to key physiological influence on homeostasis and signaling. Please fill out the CAPTCHA below and then click the button to indicate that you agree to these terms. If you wish to be unblocked, you must agree that you will take immediate steps to rectify this issue. If you do not understand what is causing this behavior, please contact us here. If you promise to stop (by clicking the Agree button below), we'll unblock your connection for now, but we will immediately re-block it if we detect additional bad behavior. Overusing our search engine with a very large number of searches in a very short amount of time.Using a badly configured (or badly written) browser add-on for blocking content.Running a "scraper" or "downloader" program that either does not identify itself or uses fake headers to elude detection.Using a script or add-on that scans GameFAQs for box and screen images (such as an emulator front-end), while overloading our search engine.There is no official GameFAQs app, and we do not support nor have any contact with the makers of these unofficial apps. Continued use of these apps may cause your IP to be blocked indefinitely. This triggers our anti-spambot measures, which are designed to stop automated systems from flooding the site with traffic. Some unofficial phone apps appear to be using GameFAQs as a back-end, but they do not behave like a real web browser does.Using GameFAQs regularly with these browsers can cause temporary and even permanent IP blocks due to these additional requests. If you are using Maxthon or Brave as a browser, or have installed the Ghostery add-on, you should know that these programs send extra traffic to our servers for every page on the site that you browse.The most common causes of this issue are: Your IP address has been temporarily blocked due to a large number of HTTP requests.
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