By default the partial charges in a force field calculation are zero. The UFF forcefield has some very rudimentary partial charges guessing, only setting charges for atoms in water molecules. Disabling energy terms ¶īy default all force field energy terms are calculated, however, you can disable each one of them individually.Įxpert key, that allows you to disable specific energy terms. Larger values will make the real-space summation faster but less accurate. Alternatively, if the is set but is not then the value affects the. Value of the error function that should be used to determine the cutoff radius for real-space Ewald summation if is set on input. Zero means the internal defaults will be used depending on the (if Alpha=0 then the cutoff will be set to 50 Bohr, otherwise to 20 Bohr). Set the cutoff value for the real-space summation. Using a larger value may require a smaller GridSpacing to be accurate. Smaller grid spacing will make the reciprocal energy calculation more accurate but slower. Grid spacing in the particle mesh Ewald method. ![]() Set to false to use real-space pair summation instead of the Ewald, which is the default and the only option for molecules, 1D and 2D periodic systems. Negative value means the will be determined automatically from the and values. Set to zero to disable the reciprocal-space Ewald part. Using a larger without decreasing may increase the error in the reciprocal-space contribution. This parameter shifts the workload from real space (smaller alpha) to reciprocal space (larger alpha). If you have questions about running i-PI calculations, or including new features into the code, you can get help on the user forum, or on the github pages.Configures the details of the particle mesh Ewald (PME) summation of the Coulomb interaction. If you are interested in interfacing your code to i-PI please get in touch, we are always glad to help!Ī few machine-learning potentials are also interfaced with i-PI, such as n2p2 (interface through LAMMPS), sGDML, AMS, and others. If you know a code that is missing in this list, please contact the developers. ![]() 236, 214–223 (2018)Īs of today, the following electronic-structure codes provide out-of-the-box an i-PI interface: CP2K, DFTB+, LAMMPS, Quantum ESPRESSO, Siesta, FHI-aims, Yaff, deMonNano, plumed, ASE, TBE, CASTEP, AMS. If you find it useful for your research, please cite us: To get the most up-to-date version, fetch it from the official i-PI repo. You are welcome to dowload, use, modify and redistribute it. I-PI is free software, distributed under a dual MIT/GPLv3 licence. ![]() Other types of electronic-structure information can also be communicated for performing advanced types of dynamics. The implementation is based on a client-server paradigm, where i-PI acts as the server and deals with the propagation of the nuclear motion, whereas the calculation of the potential energy, forces and the potential energy part of the pressure virial is delegated to one or more instances of an external code, acting as clients. The main goal is to decouple the problem of evolving the ionic positions to sample the appropriate thermodynamic ensemble and the problem of computing the inter-atomic forces. I-PI is a universal force engine interface written in Python, designed to be used together with an ab-initio, machine-learned, or force-field based evaluation of the interactions between the atoms.
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