Let $$p_t^o$$ denote the opening price at time $$t$$, and $$p_t^c$$ the closing price at time $$t$$. The return in a 5-min bar is: $$(p_{t+5}^{c}-p_t^{o})/p_t^{o}$$. For example, the first return in a given day is: $$(p_{9:35}^{c}-p_{9:30}^{o})/p_{9:30}^{o}$$
Daily return is:$$(p_{4:00 PM}^{c}-p_{9:30 AM}^{o})/p_{9:30 AM}^{o}$$
Volatility-Adjusted Return is: $$\frac{\text{Daily Return}}{\sqrt{\text{Sum of Squared 5-min. Returns}}}$$