If you are using the SHARC code, please cite the following references.
For the code:

• S. Mai, M. Richter, M. Heindl, M. F. S. J. Menger, A. Atkins, M. Ruckenbauer, F. Plasser, L.M. Ibele, S. Kropf, M. Oppel, P. Marquetand, L. González
  SHARC2.1: Surface Hopping Including Arbitrary Couplings – Program Package for Non-Adiabatic Dynamics, sharc-md.org (2019).

Please also do not forget to cite the references, where the method is described:

• M. Richter, P. Marquetand, J. González-Vázquez, I. Sola, L. González
  SHARC – ab initio molecular dynamics with surface hopping in the adiabatic representation including arbitrary couplings
  J. Chem. Theory Comput. 7, 1253-1258 (2011).
• S. Mai, P. Marquetand, L. González
  Nonadiabatic Dynamics: The SHARC Approach
  WIREs Comput. Mol. Sci., 8, e1370 (2018).

For your convenience, please find the references below in different formats.

BibTex:
@Misc{sharc-md2.1,
Title = {SHARC2.1: Surface Hopping Including Arbitrary Couplings — Program Package for Non-Adiabatic Dynamics},
Author = {Sebastian Mai and Martin Richter and Moritz Heindl and Maximilian F. S. J. Menger and Andrew Atkins and Matthias Ruckenbauer and Felix Plasser and Lea Maria Ibele and Simon Kropf and Markus Oppel and Philipp Marquetand and Leticia Gonz\’alez},
HowPublished = {sharc-md.org},
Year = {2019}
}
@Article{Richter2011JCTC,
Title = {{SHARC}: ab initio Molecular Dynamics with Surface Hopping in the Adiabatic Representation Including Arbitrary Couplings},
Author = {Martin Richter and Philipp Marquetand and Jes\'{u}s Gonz\'{a}lez-V\'{a}zquez and Ignacio Sola and Leticia Gonz\'{a}lez},
Journal = {J. Chem. Theory Comput.},
Year = {2011},
Number = {5},
Pages = {1253-1258},
Volume = {7},
Doi = {10.1021/ct1007394},
Url = {http://dx.doi.org/10.1021/ct1007394}
}
@Article{Mai2018WCMS,
Title = {Nonadiabatic Dynamics: The SHARC Approach},
Author = {Sebastian Mai and Philipp Marquetand and Leticia Gonz\’alez},
Journal = {WIREs Comput. Mol. Sci.},
Year = {2018},
Volume = {8},
Pages = {e1370},
Doi = {10.1002/wcms.1370},
Keywords = {ab initio molecular dynamics, excited states, nonadiabatic dynamics, surface hopping, SHARC},
Url = {http://dx.doi.org/10.1002/wcms.1370}
}

RIS:
TY – GEN
AU – Mai, Sebastian
AU – Richter, Martin
AU – Heindl, Moritz
AU – Menger, Maximilian F. S. J.
AU – Atkins, Andrew
AU – Ruckenbauer, Matthias
AU – Plasser, Felix
AU – Lea Maria Ibele
AU – Simon Kropf
AU – Oppel, Markus
AU – Marquetand, Philipp
AU – González, Leticia
T1 – SHARC2.1: Surface Hopping Including Arbitrary Couplings — Program Package for Non-Adiabatic Dynamics
Y1 – 2019

ER –
TY – JOUR
AU – Richter, Martin
AU – Marquetand, Philipp
AU – González-Vázquez, Jesús
AU – Sola, Ignacio
AU – González, Leticia
T1 – SHARC: ab initio Molecular Dynamics with Surface Hopping in the Adiabatic Representation Including Arbitrary Couplings
JO – J. Chem. Theory Comput.
Y1 – 2011
VL – 7
IS – 5
SP – 1253
EP – 1258
UR – http://dx.doi.org/10.1021/ct1007394
M3 – 10.1021/ct1007394

ER –
TY – JOUR
AU – Mai, Sebastian
AU – Marquetand, Philipp
AU – González, Leticia
T1 – Nonadiabatic Dynamics: The SHARC Approach
JO – WIREs Comput. Mol. Sci.
Y1 – 2018
VL – 8
SP – e1370
EP –
UR – http://dx.doi.org/10.1002/wcms.1370
M3 – 10.1002/wcms.1370
KW – ab initio molecular dynamics
KW – excited states
KW – surface hopping
KW – nonadiabatic dynamics
KW – SHARC