Existence of 'Darboux chart' on loop space

For a finite dimensional symplectic manifold $(M,\omega )$ with a symplectic form $\omega$, corresponding loop space ($LM=C^{\mathrm{\infty }}(S^1,M)$) admits a weak symplectic form ${\mathrm{\Omega }}^{\omega }$. We prove that the loop space over ${\text{mbr}}^n$ admits Darboux chart for the weak symplectic structure ${\mathrm{\Omega }}^{\omega }$. Further, we show that inclusion map from the symplectic cohomology (as defined by Kriegl and Michor \cite{KM}) of the loop space over ${\mathbb{R}}^n$ to the De Rham cohomology of the loop space is an isomorphism.