A new algorithm for efficient and fully time-reversible integration of {\it first-principles} molecular dynamics based on orbital-free density functional theory (OFDFT) is presented. The algorithm adapts to this nontrivial case the recently introduced Mass-Zero (MaZe) constrained dynamics. The formalism ensures that full adiabatic separation is enforced between nuclear and electronic degrees of freedom and, consequently, that the exact Born-Oppenheimer probability for the nuclei is sampled. Numerical integration of the MaZe dynamics combines standard molecular dynamics algorithms, e.g. Verlet or velocity Verlet, with the SHAKE method to impose the minimum conditions on the electronic degrees of freedom as a set of constraints. The developments presented in this work, that include a bespoke adaptation of the standard SHAKE algorithm, ensure that the quasilinear scaling of OFDFT is preserved by the new method for a broad range of kinetic and exchange-correlation functionals, including nonlocal ones.The efficiency and accuracy of the approach is demonstrated via calculations of static and dynamic properties of liquid sodium in the constant energy and constant temperature ensembles.

In this paper we present the Open Software Services for Classrooms and Research (OSSCAR) platform. OSSCAR provides an open collaborative environment to develop, deploy and access educational resources in the form of web applications. To minimize efforts in the creation and use of new educational material, it combines software tools that have emerged as standards with custom domain-specific ones. The technical solutions adopted to create and distribute content are described and motivated on the basis of reliability, sustainability, ease of uptake and use. Examples from courses in the domains of physics, chemistry, and materials science are shown to demonstrate the style and level of interactivity of typical applications. The tools presented are easy to use, and create a uniform and open environment exploitable by a large community of teachers, students, and researchers with the goal of facilitating learning and avoiding, when possible, duplication of efforts in creating teaching material. Contributions to expand the educational content of the OSSCAR project are welcome.

A new algorithm for efficient and fully time-reversible integration of first-principles molecular dynamics based on orbital-free density functional theory (OFDFT) is presented. The algorithm adapts to this nontrivial case the recently introduced Mass-Zero (MaZe) constrained dynamics. The formalism ensures that full adiabatic separation is enforced between nuclear and electronic degrees of freedom and, consequently, that the exact Born-Oppenheimer probability for the nuclei is sampled. Numerical integration of the MaZe dynamics combines standard molecular dynamics algorithms, e.g. Verlet or velocity Verlet, with the SHAKE method to impose the minimum conditions on the electronic degrees of freedom as a set of constraints. The developments presented in this work, that include a bespoke adaptation of the standard SHAKE algorithm, ensure that the quasilinear scaling of OFDFT is preserved by the new method for a broad range of kinetic and exchange-correlation functionals, including nonlocal ones. The efficiency and accuracy of the approach is demonstrated via calculations of static and dynamic properties of liquid sodium in the constant energy and constant temperature ensembles.

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