change index wording

content/index.txt

@@ -2,22 +2,30 @@ Quantum transport simulations made easy
 =======================================
 
 Kwant is a Python package for numerical calculations on tight-binding models
-with a strong focus on quantum transport.  It is designed to be flexible, easy to
-use, while not sacrificing performance.
-
-Tight-binding models are ubiquitous in quantum physics and they can be found in a vast variety of
-situations including graphene, quantum Hall effect, topological insulators, superconductivity, semi-conductors,
-spintronics, molecular electronics, any combination of the above and many other cases. 
-While all these systems have very distinct physics, their mathematical description is very close. 
-Kwant has been designed so that their computer implementation is also very close: changing a few lines of code is all that is needed to go from one example to another.  
-
-Kwant does not use the traditional ‘input' files often found in scientific softwares. Instead, one write small python
-programs (benefiting from python simple and very powerful syntax) to "make" the sample and "measure" its quantum properties
-(conductance, density of states, etc). Learning to use Kwant is very fast, no more than a couple of hours are needed to get started.
-You can find how easy it is to use in practice by going through the `tutorial </docs/tutorial/>`_ or  Kwant main `article </paper>`_.
-
-Kwant is provided to the physics community as an open source free software (we merely ask you to quote Kwant article in scientific publications where
-Kwant was used). Below is a rapid survey of a few applications of Kwant.
+with a strong focus on quantum transport.  It is designed to be flexible and
+easy to use, while not sacrificing performance.
+
+Tight-binding models are ubiquitous in quantum physics and they can be used to
+describe a vast variety of systems and phenomena, such as semiconductors,
+metals, graphene, topological insulators, quantum Hall effect,
+superconductivity, spintronics, molecular electronics, any combination of the
+above and many other things.  While all these systems exhibit very distinct
+physical behavior, the underlying mathematical description is very similar.
+Kwant has been designed so that the computer simulation of various physical
+systems and phenomena is within reach of one software package.
+
+Kwant does not use the traditional input files often found in scientific
+software packages. Instead, one writes simple Python programs (using the
+Python's simple and very expressive syntax) to define the system and calculate
+its quantum properties (conductance, density of states, etc). Kwant was
+designed to be easy to use, and accessible for people without expertise in
+numerics. It also comes with a detailed hand-on `tutorial </docs/tutorial/>`_
+and the Kwant `paper </paper>`_, which describes the guiding principles
+underlying its design.
+
+Kwant is provided to the physics community as an open source free software (we
+merely ask you to quote Kwant article in scientific publications where Kwant
+was used). Below a few research applications of Kwant are shown.
 
 
 conductance of a Corbino disk in a quantum Hall regime