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============================= The KIM API package =============================

This file provides an introduction to the KIM API package.  This is the first
file that you should read after unpacking the package.  See the INSTALL file
for instructions on how to build and install the package

OVERVIEW:

Atomistic or molecular simulations of materials have the potential to play a
key role in the development of innovative technology to address many problems
the world is currently facing (including climate change, energy generation and
distribution, and terrorism).  Recent examples, where valuable contributions
and greater insight have been obtained, include applications in chemistry and
organic chemistry, nanoindentation and tribology, materials processing and
properties, and nanotechnology and nanofluidics.  To model the large numbers of
particles required for many applications, and to be able to study their
dynamics over reasonable time scales, it is generally necessary to develop
approximate models of interatomic bonding, referred to as "interatomic
potentials" or "interatomic models".  Once such a model is at hand, one can in
principle predict almost any mechanical property (and some thermal properties)
of the element (or elements) it purports to describe.  Generally, these models
define the forces and energies used for sophisticated simulations using
methodologies such as molecular dynamics, Monte Carlo, lattice dynamics free
energy methods, and multiscale methods. From such simulations, complex material
properties and phenomena can be extracted, including such things as melting
temperatures, solid-liquid interface phenomena, fracture properties, and
dislocation nucleation and motion.

This software package is an implementation of the application programming
interface (API) standard for interatomic models developed as part of the Open
Knowledgebase of Interatomic Models (OpenKIM) project.  OpenKIM
(https://openkim.org) is a current initiative to develop and implement
standards for the atomistic simulation of materials.  The effort aims to help
bring order to the efforts of the academic, research, and industry
communities and to make it easier for new (and existing) scientists to leverage
the work of others in this important field.  The OpenKIM project has several
main objectives:

1. Development of an online open resource for standardized testing and
   long-term warehousing of interatomic models (potentials and force fields)
   and data.

2. Development of an API standard for atomistic simulations, which will allow
   any interatomic model to work seamlessly with any atomistic simulation code.

3. Fostering the development of a quantitative theory of transferability of
   interatomic models to provide guidance for selecting application-appropriate
   models based on rigorous criteria, and error bounds on results.

4. Striving for the permanence of the KIM project, including development of a
   sustainability plan, and establishment of a long-term home for its content.


THE KIM API PACKAGE:

The KIM API package is a system-level library that aims to give computer
programmers the ability to write atomistic or molecular simulation programs
that can seamlessly interface with implementations of interatomic models,
regardless of the programming language (C, C++, FORTRAN 77, Fortran 90/95/2003,
Python, etc.) in which the codes are written.

This version of the KIM API package is distributed under the CDDL Open Source
License.

The current version of the KIM API package supports the following features:

* Currently supported programming languages:
  C, C++, FORTRAN 77, Fortran 90/95, Fortran 2003.

* Support for automatic translation between zero-based lists (C-style numbering
  beginning with 0) and one-based lists (Fortran-style numbering beginning
  with 1)

* Communication of an arbitrary number of `arguments' between a `Model'
  (interatomic potential) and a `Simulator' (simulation code that uses a
  Model).  This is facilitated by the use of `KIM descriptor files' (whose
  names end with a `.kim' extension) and a single KIM API object data structure
  that stores all information to be communicated between a Model and a
  Simulator.

* Data types: integer, float, double, method (for exchanging pointers to
              functions), pointer (for exchanging "everything else").  Each of
              these data types can be use to create multi-dimensional array
              `arguments' that are exchanged between Models and Simulators.

     Currently, the KIM API does not define any (more complex) data structures.
     However, in the future (as the need arises, and in consultation with the
     atomistic and molecular simulation community) additional data types and
     data structures may be introduced.

* Physical Units: The KIM API supports the specification of physical units for
  each `argument' exchanged between a Model and Simulator.  A Model is either
  `fixed' or `flexible' with regard to units.  `fixed' means it is unable to
  convert to a different set of units.  `flexible' means it can convert its
  values to the Simulator's units.

* (deprecated) Neighbor lists and Boundary Conditions (NBC) methods: To
  facilitate computational efficiency, the KIM API defines a number of standard
  methods by which a Simulator may provide a Model with information about the
  neighbors of each particle in a configuration.  These currently include
  options that allow for common techniques, such as the use of the `minimum
  image' convention for orthogonal periodic boundary conditions, `padding
  particles', and neighbor lists with relative position vectors and `image
  particles'.

* Neighbor list routines are expected to be provided by the calling Simulator.
  The API provides support for `Locator' and (deprecated) `Iterator' neighbor
  list modes.  (A `Locator' returns the list of neighbors of a specified
  particle.  An (deprecated) `Iterator' works by incrementing a particle
  counter and returning the identity of the next particle (i.e. its number) and
  its neighbors.)  The API also supports (deprecated) half (symmetric and
  unsymmetric) and full neighbor lists.

* Particle Species: The KIM API provides the ability to designate the physical
  species of each particle in a simulation.  Currently, only one identifier is
  provided for each element in the periodic table.  In the future support for
  Models that require multiple types of each element will be added.

* Model Parameters: The OpenKIM philosophy views a `Model' as a well-defined
  computational code that includes fixed specific values for all parameters
  needed to perform an actual computation.  However, it is often useful to
  explore how a Model's predictions vary as the values of its parameters are
  varied.  For this reason, the KIM API provides the ability for a Model to
  `publish' its parameters so that a Simulator may modify them during the
  course of a simulation.

* Model Drivers: The KIM API package provides the ability to create Model
  Driver routines.  A Model for a given material can be created from a Model
  Driver by providing a file or files with the appropriate parameter values for
  the material of interest.

For more information on all of the above, see the files in the docs directory
described below.  Features planned for future releases are described in the
TODO file in this directory.  (See list of directory contents below.)

Your next step after reading this file is to install the KIM API package.  See
the detailed instructions in the INSTALL file in this directory.

-------------------------------------------------------------------------------

This directory (by default, kim-api-vX.Y.Z) contains the following files and
directories:

INSTALL
     A set of detailed instructions on how to install the KIM API package.

LICENSE.CDDL
     The Common Development and Distribution License (CDDL) Version 1.0 file.

Makefile
     Makefile for compiling the KIM API library and examples.

Makefile.KIM_Config.example
     Example Makefile.KIM_Config file.  This file provides the basic settings
     needed to build the KIM API system and associated Model Drivers, Models,
     and the provided examples.

Makefile.Version
     Makefile containing variable definitions for the complete SemVer version
     of the KIM API package.

NEWS
     A list of main changes made for each KIM API release.

README
     This file.

TODO
     A file listing features planed for future releases of the KIM API package.

build_system/
     A directory containing the common Makefiles and default settings used by
     the KIM API package build system.

configure
     A shell script to configure the KIM API and create a Makefile.KIM_Config
     file.

docs/
     Documentation directory.  This directory contains the file
     kim-api-vX.Y.Z-introduction.pdf which provides an overview of this release
     of the KIM API package, the file KIM_API_Descriptions.txt, a link to the
     file standard.kim, and a templates directory containing template files for
     creating your own KIM Models.  (See the README file in that directory.)

examples/
     A directory containing examples of interatomic Model Drivers, Models,
     Simulators, and OpenKIM Tests.

src/
     A directory containing the KIM API source code.

*******************************************************************************

SUPPORT

If you have problems or questions, send an email with your question and all
relevant information to

openkim@googlegroups.com

The members of the OpenKIM development team actively monitor this email list
and will do their best to help you with your question in a timely fashion.

*******************************************************************************
