Conquest is a linear scaling, or O(N), DFT electronic structure code developed jointly by NIMS (National Institute for Materials Science, Japan) and UCL. The code is designed to perform DFT calculations on very large systems (containing tens of thousands, hundreds of thousands or even millions of atoms). It can be run at different levels of precision, ranging from ab initio tight binding up to full DFT with plane wave accuracy. It is capable of operation on a range of platforms from workstations up to high performance computing centres. These web pages contain information on the code, and its applications, as well as separate areas for developers.
We have recently written a comprehensive review of O(N) methods, which you can find here (external link).
You can find out more about Conquest in these pages:
DFT study of undoped and As-doped Si nanowires approaching the bulk limit
Measuring the effects of quantum interference on charge transport
Calculating the properties of a graphene-metal system on a large scale
Studying the structural properties of Si/Ge and Ge/Si core-shell nanowires
O(N) DFT and Sakurai–Sugiura method efficiently simulating 10000+ atoms