A new method is introduced for accurately and efficiently describing many-body van der Waals (vdW) interactions in molecules and solids. This method combines the Tkatchenko-Scheffler (TS) vdW approach with a self-consistent screening equation from classical electrodynamics. The TS-vdW method calculates vdW energy using the ground-state electron density and includes hybridization effects for polarizability. However, it neglects long-range electrostatic screening. The new method incorporates this screening effect through a self-consistent screening (SCS) equation, which accounts for the dynamic electric field created by surrounding atoms, leading to polarization and depolarization effects. This approach improves the description of anisotropy in molecular polarizability and enhances the accuracy of vdW energy calculations. The SCS equation is solved for a system of coupled oscillators, leading to a frequency-dependent polarizability tensor that includes both short-range (via TS-vdW) and long-range (via SCS) screening effects. This method is applied to small molecules and solids, showing significant improvements in the accuracy of conformational energies for biomolecules and binding in molecular crystals. The computational cost is negligible compared to the underlying electronic structure calculation. The method is extended to include many-body vdW energy using the coupled fluctuating dipole model (CFDM). This allows for the computation of many-body effects beyond the pairwise approximation. The CFDM Hamiltonian is solved to compute the vdW interaction energy between quantum harmonic oscillators, which is then used to calculate the many-body vdW energy. The method is benchmarked on the S22 database of intermolecular interactions, showing a significant reduction in mean absolute relative error (MARE) compared to other methods. It also performs well in predicting the conformational energies of alanine tetrapeptide, demonstrating its accuracy in biomolecular simulations. The inclusion of SCS and many-body dispersion (MBD) effects is crucial for achieving chemical accuracy in simulations of extended systems, such as the benzene molecular crystal, where the cohesive energy is accurately predicted. The method is efficient and applicable to finite-gap molecules and condensed matter systems. It uses a single physically motivated range-separation parameter for a given DFT functional, enabling accurate and efficient calculations of vdW interactions. The method significantly improves the binding energies for small molecules and shows pronounced improvements for larger, more complex systems, paving the way for molecular dynamics simulations with the full many-body treatment of vdW interactions.A new method is introduced for accurately and efficiently describing many-body van der Waals (vdW) interactions in molecules and solids. This method combines the Tkatchenko-Scheffler (TS) vdW approach with a self-consistent screening equation from classical electrodynamics. The TS-vdW method calculates vdW energy using the ground-state electron density and includes hybridization effects for polarizability. However, it neglects long-range electrostatic screening. The new method incorporates this screening effect through a self-consistent screening (SCS) equation, which accounts for the dynamic electric field created by surrounding atoms, leading to polarization and depolarization effects. This approach improves the description of anisotropy in molecular polarizability and enhances the accuracy of vdW energy calculations. The SCS equation is solved for a system of coupled oscillators, leading to a frequency-dependent polarizability tensor that includes both short-range (via TS-vdW) and long-range (via SCS) screening effects. This method is applied to small molecules and solids, showing significant improvements in the accuracy of conformational energies for biomolecules and binding in molecular crystals. The computational cost is negligible compared to the underlying electronic structure calculation. The method is extended to include many-body vdW energy using the coupled fluctuating dipole model (CFDM). This allows for the computation of many-body effects beyond the pairwise approximation. The CFDM Hamiltonian is solved to compute the vdW interaction energy between quantum harmonic oscillators, which is then used to calculate the many-body vdW energy. The method is benchmarked on the S22 database of intermolecular interactions, showing a significant reduction in mean absolute relative error (MARE) compared to other methods. It also performs well in predicting the conformational energies of alanine tetrapeptide, demonstrating its accuracy in biomolecular simulations. The inclusion of SCS and many-body dispersion (MBD) effects is crucial for achieving chemical accuracy in simulations of extended systems, such as the benzene molecular crystal, where the cohesive energy is accurately predicted. The method is efficient and applicable to finite-gap molecules and condensed matter systems. It uses a single physically motivated range-separation parameter for a given DFT functional, enabling accurate and efficient calculations of vdW interactions. The method significantly improves the binding energies for small molecules and shows pronounced improvements for larger, more complex systems, paving the way for molecular dynamics simulations with the full many-body treatment of vdW interactions.