Installing-the-toolkit.md

+# Requirements
+## Static codes (st-wslda)
+* C compiler (eg. `gcc`, intel compiler `icc`, ...)
+* MPI C compiler (eg. `mpicc`, intel compiler `mpiicc`, ...)
+* [FFTW library](http://www.fftw.org/)
+* LAPACK library
+* ScaLAPACK library
+* [ELPA library](https://elpa.mpcdf.mpg.de/) (optionally)
+* [CUDA compiler](https://docs.nvidia.com/cuda/cuda-compiler-driver-nvcc/index.html) (optionally, for ELPA)  
+
+*Note 1*: compilers and libraries (FFTW, LAPACK, ScaLAPACK) are installed by default on most of computing clusters. If computing system is equipped with GPUs most likely CUDA Toolkit is also installed. On many systems ELPA is also installed by default. If not you can compile it yourself. 
+
+*Note 2*: It is recommend to use `st-wslda` with ELPA support if possible. It provides substantial speed-up of computation process.
+
+## Time-dependent codes (td-wslda)
+* C compiler (eg. `gcc`, intel compiler `icc`, ...)
+* MPI C compiler (eg. `mpicc`, intel compiler `mpiicc`, ...)
+* [CUDA compiler](https://docs.nvidia.com/cuda/cuda-compiler-driver-nvcc/index.html)   
+
+*Note 1*: Time dependent codes **require** systems accelerated by GPUs. `td-wslda` codes cannot run on standard systems based on CPUs only.
+
 # Downloading the toolkit
 It is recommended to download the toolkit directly from repository using git
 ```bash