  In this study, a formal definition, robustness analysis and discussion on the
control of a position-based semiconductor charge qubit are presented. Such a
qubit can be realized in a chain of coupled quantum dots, forming a register of
charge-coupled transistor-like devices, and is intended for CMOS implementation
in scalable quantum computers. We discuss the construction and operation of
this qubit, its Bloch sphere, and relation with maximally localized Wannier
functions which define its position-based nature. We then demonstrate how to
build a tight-binding model of single and multiple interacting qubits from
first principles of the Schr\"odinger formalism. We provide all required
formulae to calculate the maximally localized functions and the entries of the
Hamiltonian matrix in the presence of interaction between qubits. We use three
illustrative examples to demonstrate the electrostatic interaction of electrons
and discuss how to build a model for many-electron (qubit) system. To conclude
this study, we show that charge qubits can be entangled through electrostatic
interaction.
