The LAMMPS categories on MatSci.org are the primary way to get help with *installing, running, programming* the [LAMMPS Molecular Dynamics software package](https://www.lammps.org/) and to facilitate exchange between LAMMPS users and developers. The main motivation of using a forum is that this allows *anybody* to join a discussion and try to provide assistance, even those with limited experience. As the LAMMPS community is growing, this allows that the pool of people that can potentially help others is growing. Keep in mind that users are often better equipped to explain how to use software effectively to other users than the developers. Please always keep in mind that people here are volunteering their time. So please be respectful to anybody that makes the effort to respond to your posts. Below are several guidelines to assist with using the forum effectively and to avoid wasting anybody's time. Thus please read them carefully. You can click on the triangles to see more detailed explanations for the individual guidelines. [details="What you should not expect from this forum"] Since this forum is dedicated on the use of the LAMMPS software, keep in mind that it is in no way a replacement for: - Operating softwares manuals (Linux, Mac or Windows) - Programming lesson - Physics or chemistry class - Literature research engine The practice and learning of science is better done in direct contact with people. As such an advisor or a colleague which you can directly explain your problem to is very likely to provide more meaningful help than people on the internet that you do not know about and who do not know anything about you or your research. This is also valid for installation related problems, as your local system administrator is the person that will know the most about your system. [/details] [details="Post in the correct category"] The MatSci.org server hosts discussion forums for multiple materials science related topics and multiple softwares. To have your post show up in the LAMMPS related area where other LAMMPS users and enthusiasts can see and respond to it. Do *not* use the default. To organize discussions within the LAMMPS category there are sub-categories. Please always choose the most appropriate one: - LAMMPS Beginners: for people that are not very experienced with using LAMMPS. People will be more forgiving if you make mistakes, but don't be offended when you get explanations for what you already know - LAMMPS Development: for discussions about programming LAMMPS, using the library interface or python module or possible bugs - LAMMPS Installation: for questions about compiling or installing LAMMPS - LAMMPS General Discussion: for all other topics. This assumes that you know the science, so responses may just point you to a source of information. Don't be offended when not all details are explained Questions related to pre-processing, post-processing or visualisation of your data using softwares other than LAMMPS are very likely to fall outside of the LAMMPS forum scope. These would better be posted using the dedicated channels related to the software you are using. [/details] [details="Always report your LAMMPS version and platform"] The behavior of LAMMPS changes over time. New features are added, obsolete ones removed, syntax changed and more. Mentioning the exact version of LAMMPS being used (it is printed as the first line of output or at the top of `lmp -h`) can be crucial information for anybody trying to provide an answer. Please do not use terms like "the latest version" or "the stable version". Those can be very different depending on how you obtain LAMMPS and they will change over time. The LAMMPS version has the format of a date (Ex: 8 Feb 2023). This is what you should report. Reporting the LAMMPS version helps significantly, because the developers remember when a similar problem came up, and can tell if you are encountering a bug that has already been fixed. Note that if you are using a old version and your problem is something that many users would run into, like a bug with input or output, then you might be told to upgrade to the most current version to see if your problem goes away. [/details] [details="Be concise and specific; do not make any assumptions about what people know"] The quality of any assistance you can get crucially depends on several things. For example: - how well you describe your problem - what solutions you have tried - how easy it is to reproduce your issue Most users of the forum are not likely experts in your specific area of research. Thus avoid domain specific slang terms (specific acronymes and so on), explain all details relevant for a non-expert, and try to simplify your input to focus on the problem at hand. It is important for other readers to understand how what you expected differs from your obtained. The **worst** you could do is to attach your input and say "it doesn't work". Competent and helpful responses require context. This kind of post has none. [/details] [details="Be sure to research your problem before posting"] It is always better to show that you have already tried to solve your problem on your own before asking for help. Be sure to read the [LAMMPS manual](https://docs.lammps.org/Manual.html) sections that correspond to the commands you used. Also, before asking what a given error/warning message means, please be sure to read the [dedicated section](https://docs.lammps.org/Errors.html) from the manual. This section contains information related to common errors, how to report a bug and detailed descriptions of the error and warning messages. If you don't know what line in your input script is causing LAMMPS to generate an error, then use the -echo screen command-line option when you run LAMMPS. If you are having a problem with a specific input script command, carefully read the entire doc page associated with that command. There may be text somewhere on that page which answers your question. As many people use the LAMMPS software, it is likely that someone had the same issues you currently have and expect to post about. You can research previous posts using the research function of the forum before posting. Some questions have been answered dozen of times and the forum already contain a lot of informations. In addition to the forum posts, the LAMMPS forum contains archives of the old mailing-list that ran from 2005 to june 2022. These archives are also accessible through the search function. In the case where you find a thread relating/responding to a problem similar to yours, please *do not post in this thread*. This is called necroposting and is very bad forum practice. If you're not able to find a solution to your issue, create a new dedicated thread. [/details] [details="Format your post so it is readable"] The LAMMPS forum posts are formatted using Markdown and BBCode. Markdown is a simple markup language that uses special characters such as \* \$ and other to render equation, bold words, titles etc. BBCode's spirit is the same but with some tag system. This has two main consequences: 1. **PLEASE: Do not copy and paste your LAMMPS input file as is.** The formating will make your post impossible or very hard to read. In any case, avoid posting your full file if it is too big and try to isolate the commands that you think are causing the problem. If you then want to copy and paste lines from your file, enclose them between three backtick characters (\`\`\`). Be sure to use backticks \` and not apostrophes '. 2. You can format your post to make it easier to read and go through. Markdown is easy to grasp and even has a dedicated 10mn tutorial on the [Commonmark website](https://commonmark.org/help/). Do not hesitate to go through it. You can also have a look at the [BBCode tag system](https://www.bbcode.org/reference.php). The forum offers preview of your messages before posting. Please use that to format your posts beforehand. You can also edit your post afterward. [/details] [details="Take a look at your simulation"] It is always a good idea to have a look at what is happening in your simulations. If your results make no sense, be sure to check if something catastrophic is not happening or if your starting configuration is not bogus to begin with. LAMMPS data and dump files can be visualised with several softwares. You can see a incomplete list on the [LAMMPS website](https://www.lammps.org/viz.html). If your simulation is not going according to what you expected, do not assume firsthand that the software is doing things wrong. It is very common that an unphysical simulation actually results from some bad combination of commands or some wrong starting setup. [/details]