A new molecular dynamics model is introduced where atomic charges are allowed to fluctuate in response to the environment, applied to water. The model is based on the concept of electronegativity equalization, where charges are adjusted to equalize electronegativities. Charges are treated as dynamical variables using an extended Lagrangian method, introducing fictitious mass and velocities. The model is applied to water using geometries from the SPC and TIP4P potentials, which are widely used for simulating water. Both fluctuating charge models give accurate predictions for gas-phase and liquid state properties, including radial distribution functions, dielectric constant, and diffusion constant. The method does not introduce new intermolecular interactions and increases computational time by only a factor of 1.1, making it tractable for large systems. The model uses electronegativity equalization to determine charges, with parameters calculated using density functional theory or empirical data. The charges are treated as dynamical variables, and the model accounts for charge transfer between atomic sites. The model is implemented using molecular dynamics, with periodic boundary conditions and the Ewald sum for long-range electrostatic interactions. The model is tested on water monomers, dimers, and liquid water, showing improved static and dynamic properties compared to fixed charge models. The model accurately predicts the dielectric constant, radial distribution functions, and diffusion constants. The fluctuating charge models show better agreement with experimental results for the dielectric constant and other properties compared to fixed charge models. The models also show features in the dielectric spectrum due to translational motion of water molecules, which are not present in fixed charge models. The models are computationally efficient and can be extended to more complex systems. The results demonstrate that fluctuating charge models provide a more accurate representation of water properties compared to fixed charge models.A new molecular dynamics model is introduced where atomic charges are allowed to fluctuate in response to the environment, applied to water. The model is based on the concept of electronegativity equalization, where charges are adjusted to equalize electronegativities. Charges are treated as dynamical variables using an extended Lagrangian method, introducing fictitious mass and velocities. The model is applied to water using geometries from the SPC and TIP4P potentials, which are widely used for simulating water. Both fluctuating charge models give accurate predictions for gas-phase and liquid state properties, including radial distribution functions, dielectric constant, and diffusion constant. The method does not introduce new intermolecular interactions and increases computational time by only a factor of 1.1, making it tractable for large systems. The model uses electronegativity equalization to determine charges, with parameters calculated using density functional theory or empirical data. The charges are treated as dynamical variables, and the model accounts for charge transfer between atomic sites. The model is implemented using molecular dynamics, with periodic boundary conditions and the Ewald sum for long-range electrostatic interactions. The model is tested on water monomers, dimers, and liquid water, showing improved static and dynamic properties compared to fixed charge models. The model accurately predicts the dielectric constant, radial distribution functions, and diffusion constants. The fluctuating charge models show better agreement with experimental results for the dielectric constant and other properties compared to fixed charge models. The models also show features in the dielectric spectrum due to translational motion of water molecules, which are not present in fixed charge models. The models are computationally efficient and can be extended to more complex systems. The results demonstrate that fluctuating charge models provide a more accurate representation of water properties compared to fixed charge models.