I would like to know how to estimate the value (length) of the lattice constant in crystals in terms of fundamental parameters such as electron charge, electron mass, proton mass and Planck constant. (Alternatively, the formula may contain the Bohr radius, since I know how to calculate Bohr radius from the fundamental parameters). I am not interested in an accurate calculation, by DFT or whatever. All I need is a simple formula that estimates the order of magnitude. If the formula can be found in a standard textbook, please tell me which textbook and a precise location (page number, equation number, etc.). Thanks!