YASARA is a molecular-graphics, -modeling and -simulation program for Android, Windows, Linux and Mac OS X developed since 1993, that finally makes it really easy to answer your questions.
YASARA is an acronym for 'Yet Another Scientific Artificial Reality Application', which points to one of its core features: ultra-fast molecular dynamics simulations, that can be visualized in real-time on screen, allowing you to interact with the 'artificial reality' and pull atoms or entire molecules around, also on smartphones and tablets. Force field parameters are assigned automatically.
YASARA is also a complete molecular modeling lab, providing all the functions you need, including docking, homology modeling and NMR structure determination, please visit http://www.yasara.org for all the details.
YASARA owes its performance and efficiency to MMX/SSE/AVX assembler code, which unfortunately requires an Android device with Intel CPU to run, but in return gives you a unique molecular modeling experience. Please visit http://www.yasara.org/android for videos and details about supported devices.
Four different YASARA stages are available, each one covering a wider range of topics. Here you can download the first stage 'YASARA View', which is free for academic and commercial use. Features include molecular graphics and basic molecular modeling (editing and analyzing molecules).
To run YASARA on Android, your device must provide a screen resolution of minimally 480x640 (smartphone) or 640x480(tablet) pixels, and 65 MB external storage space (usually at /mnt/sdcard). The first time you run YASARA, it will download the very latest version from our server, the total download size is about 40 MB.
When the download is complete, please tap 'Help > Play help movie > Working with YASARA' to get detailed usage instructions. Also watch the YouTube movie below.
If you encounter a problem or want to contact us for another reason, please write to android(a)yasara.org. We are grateful for any feedback you provide, and even pay for bug reports (http://www.yasara.org/contact). Emailing is much faster than posting a comment below, since we are lacking the time to check this page frequently.
Have fun with YASARA!