The evolution of the density matrix was investigated using the Leouville von Neuman equation with the interaction Hamiltonian having two nonzero matrix elements H$_{ij}$ = Ω$_{R}$( t − T )[exp {− i (( ω$_{L}$ + ω$_{ji}$ )( t − T ) + M ( t − T )) } + exp { i (( ω$_{L}$ − ω$_{ji}$ )( t − T ) + M ( t − T )) } ], here, i,j are the indexes of the basis set, i = 1 , 2 and j = i + 1, M ( t − T ) = Φ 0 sin Ω( t − T ) is the modulation of the phase, Ω$_{R}$( t − T ) = Ω$_{R}$ exp ( − ( t − T ) $^{2}$/ (2 τ $^{2}$)) is the Rabi frequency, and Ω$_{R}$ is the peak value of the Rabi frequency. Calculations were done beyond the rotating wave approximation, that allows for flexible values of the transition frequencies relative to the laser carrier frequencies to be considered. To get zero value of the carrier-envelope phase, the temporal variation is taken in the form of (t-T), where T is the pulse train period. It guarantees the envelope maximum to coincide with the peak value of the amplitude of the electric field. The condition for the Raman resonance is satisfied by making the difference of laser field frequency components ( ω$_{L}$ − Ω) equal to the two-photon transition frequency ω 31 . Additionally, the modes that are multiples of the radio frequency f$_{r}$ provide with pairs of optical frequencies that differ by exactly the transition frequency ω 31 . These lead to an efficient stepwise population accumulation in the final state in the λ -system. The results of population transfer are presented in the Fig.(2) for the parameters: The peak Rabi frequency Ω$_{R}$=1, the carrier frequency ω$_{L}$ =5.9, the modulation frequency Ω=4.9, the pulse duration τ = 0 . 25, and the modulation amplitude Φ 0 = 4. The λ -system transition frequencies are ω 21 =4.9, and ω 32 =5.9. Adiabatic population transfer is achieved from the initial | 1 > to the final | 3 > state via the transitional state | 2 > , which is insignificantly populated. A negligible population of the intermediate state is favorable for minimizing spontaneous emission losses. Each pulse brings a fraction of population, ( ∼ 1%), to the final state and contributes to the accumulative effect. Total population transfer occurs after 112 sequential pulses and is accomplished in 2.5 ns, which is within the lifetime of the Feshbach KRb molecules. When the carrier frequency ω$_{L}$ and the modulation frequency Ω of the optical frequency comb are detuned off resonance with the transitional frequencies ω 31 and ω 21 respectively, the stepwise adiabatic population transfer takes place in a fashion similar to the resonance case. The time evolution of population is presented in the Fig.(3) for parameters Ω$_{R}$=1, the carrier frequency ω$_{L}$ =5.4, the modulation frequency Ω=4.4, and the modulation amplitude Φ 0 = 4; the λ -system transition frequencies are ω 21 =4.9, and ω 32 =5.9, giving δ = ω 31 / 2. Figure shows the coherent accumulation of the population in the final state, taking place 5