From Classical to Quantum and Back: Hamiltonian Adaptive Resolution Path Integral, Ring Polymer, and Centroid Molecular Dynamics

Path integral-based simulation methodologies play a crucial role for the investigation of nuclear quantum effects by means of computer simulations. However, these techniques are significantly more demanding than corresponding classical simulations. To reduce this numerical effort, we recently proposed a method, based on a rigorous Hamiltonian formulation, which restricts the quantum modeling to a small but relevant spatial region within a larger reservoir where particles are treated classically. In this work, we extend this idea and show how it can be implemented along with state-of-the-art path integral simulation techniques, such as ring polymer and centroid molecular dynamics, which allow the approximate calculation of both quantum statistical and quantum dynamical properties. To this end, we derive a new integration algorithm which also makes use of multiple time-stepping. The scheme is validated via adaptive classical--path-integral simulations of liquid water. Potential applications of the proposed multiresolution method are diverse and include efficient quantum simulations of interfaces as well as complex biomolecular systems such as membranes and proteins

The Inter Vivos Rights of Cotenants Inter Se

The inter vivos rights and remedies among joint tenants with respect to their common property are in general the same as those of other co-owners of property. Differences become most apparent upon the death of one tenant. During the period when all of the joint tenants are alive, they are included in the general group, cotenants, the term for co-owners of property, and their rights and remedies for the most part fall within the rules governing co-tenants. Some exceptions will be considered here. One difference between the rules governing joint tenants and those governing other co-owners is that while service of notice concerning the common property normally binds only the tenant in common who is served, service upon a joint tenant is notice to all of the tenants. Other differences center around the rule that cotenants of property are usually in a relationship of trust and have a fiduciary duty toward one another

C−\mathcal {C}-IBI: Targeting cumulative coordination within an iterative protocol to derive coarse-grained models of (multi-component) complex fluids

We present a coarse-graining strategy that we test for aqueous mixtures. The method uses pair-wise cumulative coordination as a target function within an iterative Boltzmann inversion (IBI) like protocol. We name this method coordination iterative Boltzmann inversion ($\mathcal {C}-$IBI). While the underlying coarse-grained model is still structure based and, thus, preserves pair-wise solution structure, our method also reproduces solvation thermodynamics of binary and/or ternary mixtures. Additionally, we observe much faster convergence within $\mathcal {C}-$IBI compared to IBI. To validate the robustness, we apply $\mathcal {C}-$IBI to study test cases of solvation thermodynamics of aqueous urea and a triglycine solvation in aqueous urea

Ground state of two unlike charged colloids: An analogy with ionic bonding

In this letter, we study the ground state of two spherical macroions of identical radius, but asymmetric bare charge ((Q_{A}>Q_{B})). Electroneutrality of the system is insured by the presence of the surrounding divalent counterions. Using Molecular Dynamics simulations within the framework of the primitive model, we show that the ground state of such a system consists of an overcharged and an undercharged colloid. For a given macroion separation the stability of these ionized-like states is a function of the difference ((\sqrt{N_{A}}-\sqrt{N_{B}})) of neutralizing counterions (N_{A}) and (N_{B}). Furthermore the degree of ionization, or equivalently, the degree of overcharging, is also governed by the distance separation of the macroions. The natural analogy with ionic bonding is briefly discussed.Comment: published versio