By using variational quantum Monte Carlo techniques, we investigate the instauration of stripes (i.e., charge and spin inhomogeneities) in the Hubbard model on the square lattice at hole doping delta = 1/8, with both nearest- (t) and next-nearest-neighbor hopping (t'). Stripes with different wavelengths lambda (denoting the periodicity of the charge inhomogeneity) and character (bond- or site-centered) are stabilized for sufficiently large values of the electron-electron interaction U/t. The general trend is that lambda increases going from negative to positive values of t'/t and decreases by increasing U/t. In particular, the lambda = 8 stripe obtained for t' = 0 and U/t = 8 [L.F. Tocchio, A. Montorsi, and F. Becca, SciPost Phys. 7, 21 (2019)] shrinks to lambda = 6 for U/t greater than or similar to 10. For t'/t < 0, the stripe with lambda = 5 is found to be remarkably stable, while for t'/t > 0, stripes with wavelength lambda = 12 and lambda = 16 are also obtained. In all these cases, pair-pair correlations are highly suppressed with respect to the uniform state (obtained for large values of vertical bar t'/t vertical bar), suggesting that striped states are not superconducting at delta = 1/8.
