We consider the nonlinear Dirac (NLD) equation in 1+1 dimension with scalar-scalar selfinteraction
in the presence of external forces as well as damping of the form γͦf(x-t) - ιμγͦψ, where both f, {fj = rieiKjx} and ψ are two-component spinors. We develop an approximate variational
approach using collective coordinates (CC) for studying the time dependent response of the
solitary waves to these external forces. In our previous paper we assumed Kj = K, j = 1,2 which
allowed a transformation to a simplifying coordinate system, and we also assumed the "small" component
of the external force was zero. Here we include the effects of the small component and also
the case K1 ≠ K2 which dramatically modi es the behavior of the solitary wave in the presence of
these external forces.United States Department of EnergySanta Fe InstituteNational Natural Science Foundation of China (Nos. 11471025 and 11421101)Alexander von Humboldt Foundation (Germany) through Research Fellowship for Experienced Researchers SPA 1146358 STPMinisterio de Economía y Competitividad (Spain) through FIS2014-54497-PJunta de Andalucía (Spain) under Projects No. FQM207Excellent Grant P11-FQM-7276Mathematical Institute of the University of Seville (IMUS)Theoretical Division and Center for Nonlinear Studies at Los Alamos National LaboratoryPlan Propio of the University of Sevill