The paper introduces a new molecular dynamics model that allows point charges on atomic sites to fluctuate in response to the environment, focusing on water. The model is based on the concept of electronegativity equalization, where charges are treated as dynamical variables using an extended Lagrangian method. This approach is applied to two common fixed-charge water potentials: the simple point charge (SPC) and the 4-point transferable intermolecular potential (TIP4P). The fluctuating charge models accurately predict gas-phase and liquid state properties, including radial distribution functions, dielectric constants, and diffusion constants. The method does not introduce new intermolecular interactions beyond those in fixed-charge models and increases computational time by only a factor of 1.1, making it suitable for large systems. The paper discusses the implementation details, numerical methods, and results, showing that the fluctuating charge models improve upon fixed-charge models in terms of accuracy and computational efficiency.The paper introduces a new molecular dynamics model that allows point charges on atomic sites to fluctuate in response to the environment, focusing on water. The model is based on the concept of electronegativity equalization, where charges are treated as dynamical variables using an extended Lagrangian method. This approach is applied to two common fixed-charge water potentials: the simple point charge (SPC) and the 4-point transferable intermolecular potential (TIP4P). The fluctuating charge models accurately predict gas-phase and liquid state properties, including radial distribution functions, dielectric constants, and diffusion constants. The method does not introduce new intermolecular interactions beyond those in fixed-charge models and increases computational time by only a factor of 1.1, making it suitable for large systems. The paper discusses the implementation details, numerical methods, and results, showing that the fluctuating charge models improve upon fixed-charge models in terms of accuracy and computational efficiency.