C. Filippi, M. Zaccheddu, and F. Buda, J. Chem. Theory Comput, vol.5, p.2074, 2009.

P. M. Zimmerman, J. Toulouse, Z. Zhang, C. B. Musgrave, and C. Umrigar, J. Chem. Phys, vol.131, p.124103, 2009.

O. Valsson and C. Filippi, J. Chem. Theory Comput, vol.6, p.1275, 2010.

R. Send, O. Valsson, and C. Filippi, Journal of Chemical Theory and Computation, vol.7, p.444, 2011.

O. Valsson, P. Campomanes, I. Tavernelli, U. Rothlisberger, and C. Filippi, J. Chem. Theory Comput, vol.9, p.2441, 2013.

R. Guareschi, H. Zulfikri, C. Daday, F. M. Floris, C. Amovilli et al., Journal of Chemical Theory and Computation, vol.12, p.1674, 2016.

R. J. Hunt, M. Szyniszewski, G. I. Prayogo, R. Maezono, and N. D. Drummond, Phys. Rev. B, vol.98, p.75122, 2018.

N. S. Blunt and E. Neuscamman, J. Chem. Theory Comput, vol.15, p.178, 2019.

M. Dash, J. Feldt, S. Moroni, A. Scemama, and C. Filippi, J. Chem. Theory Comput, vol.15, p.4896, 2019.

W. M. Foulkes, L. Mitas, R. J. Needs, and G. Rajagopal, Reviews of Modern Physics, vol.73, p.33, 2001.

A. Lüchow, Wiley Interdisciplinary Reviews: Computational Molecular Science, vol.1, p.388, 2011.

B. M. Austin, D. Y. Zubarev, and W. A. Lester, Chemical Reviews, vol.112, p.263, 2012.

S. Sorella and L. Capriotti, The Journal of Chemical Physics, vol.133, p.234111, 2010.

E. Neuscamman, C. J. Umrigar, G. K. , and -. Chan, Phys. Rev. B, vol.85, p.45103, 2012.

C. Filippi, R. Assaraf, and S. Moroni, J. Chem. Phys, vol.144, p.194105, 2016.

R. Assaraf, S. Moroni, and C. Filippi, J. Chem. Theory Comput, vol.13, p.5273, 2017.

M. Dash, S. Moroni, A. Scemama, and C. Filippi, J. Chem. Theory Comput, vol.14, p.4176, 2018.

R. L. Coldwell, International Journal of Quantum Chemistry, vol.12, p.215, 1977.

C. J. Umrigar, K. G. Wilson, and J. W. Wilkins, Phys. Rev. Lett, vol.60, p.1719, 1988.

A. Malatesta, S. Fahy, and G. B. Bachelet, Phys. Rev. B, vol.56, p.12201, 1997.

P. R. Kent, R. J. Needs, and G. Rajagopal, Phys. Rev. B, vol.59, p.12344, 1999.

C. J. Umrigar and C. Filippi, Phys. Rev. Lett, vol.94, p.150201, 2005.

J. A. Shea and E. Neuscamman, Journal of Chemical Theory and Computation, vol.13, p.6078, 2017.

S. D. Pineda-flores and E. Neuscamman, J. Phys. Chem. A, vol.123, p.1487, 2019.

O. Valsson, C. Angeli, and C. Filippi, Phys. Chem. Chem. Phys, vol.14, p.11015, 2012.

M. Huix-rotllant, M. Filatov, S. Gozem, I. Schapiro, M. Olivucci et al., Journal of Chemical Theory and Computation, vol.9, p.3917, 2013.

D. Tuna, D. Lefrancois, L. Wola?ki, S. Gozem, I. Schapiro et al., Journal of Chemical Theory and Computation, vol.11, p.5758, 2015.

B. , L. Guennic, and D. Jacquemin, Accounts of Chemical Research, vol.48, p.530, 2015.

, As Jastrow factor, we use the exponential of the sum of two fifth-order polynomials of the electron-nuclear and the electronelectron distances, respectively, and rescale the inter-particle distances as R = (1 ? exp(??r))/? with ? set to 0.6 a.u. We employ different electron-nucleus Jastrow factors to describe the correlation of an elecron with C and H. The total number of free parameters

E. Neuscamman, The Journal of Chemical Physics, vol.145, p.81103, 2016.

S. Sorella, M. Casula, and D. Rocca, J. Chem. Phys, vol.127, p.14105, 2007.

I. Sabzevari, A. Mahajan, and S. Sharma, The Journal of Chemical Physics, vol.152, p.24111, 2020.

W. T. William, H. Press, A. Saul, B. P. Teukolsky, and . Flannery, Numerical Recepies Third Edition, 2007.

J. Toulouse and C. J. Umrigar, The Journal of Chemical Physics, vol.128, p.174101, 2008.

, CHAMP is a quantum Monte Carlo program package written by

M. Burkatzki, C. Filippi, and M. Dolg, J. Chem. Phys, vol.126, p.234105, 2007.

M. Dolg and C. Filippi, For the hydrogen atom, we use a more accurate BFD pseudopotential and basis set, pp.private communica- tion

R. A. Kendall, T. H. Dunning, and R. J. Harrison, J. Chem. Phys, vol.96, p.6796, 1992.

C. Attaccalite and S. Sorella, Phys. Rev. Lett, vol.100, p.114501, 2008.

M. Casula, Phys. Rev. B, vol.74, p.161102, 2006.

M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon et al., J. Comput. Chem, vol.14, p.1347, 1993.

M. S. Gordon and M. W. Schmidt, Theory and applications of computational chemistry, pp.1167-1189, 2005.

Y. Garniron, T. Applencourt, K. Gasperich, A. Benali, A. Ferté et al., Journal of Chemical Theory and Computation, vol.15, p.3591, 2019.

M. Dash and A. Scemama,

P. Boulanger, D. Jacquemin, I. Duchemin, and X. Blase, J. Chem. Theory Comput, vol.10, p.1212, 2014.

M. J. Frisch, G. W. Trucks, H. B. Schlegel, G. E. Scuseria, M. A. Robb et al., , 2016.

R. M. Parrish, L. A. Burns, D. G. Smith, A. C. Simmonett, A. E. Deprince et al., J. Chem. Theory Comput, vol.13, p.3185, 2017.

Y. Garniron, A. Scemama, E. Giner, M. Caffarel, and P. Loos, The Journal of Chemical Physics, vol.149, p.64103, 2018.